diff --git a/L3/LD_24/App_Data/Rezultatai.txt b/L3/LD_24/App_Data/Rezultatai.txt
index 8b0f319..288d333 100644
--- a/L3/LD_24/App_Data/Rezultatai.txt
+++ b/L3/LD_24/App_Data/Rezultatai.txt
@@ -3,10 +3,10 @@
 ----------------------------
 | ID |     Vardas | Kaina  |
 ----------------------------
-|  0 | Atsuktuvas | 0,99   |
-|  1 |    Varztas | 0,05   |
-|  2 |     Laidas | 2,00   |
-|  3 |  Plaktukas | 2,99   |
+|  0 | Atsuktuvas | 0.99   |
+|  1 |    Varztas | 0.05   |
+|  2 |     Laidas | 2.00   |
+|  3 |  Plaktukas | 2.99   |
 ----------------------------
 
 --------------------------------------------------
@@ -33,7 +33,7 @@
 ------------------------------------------------------------
 | ID | Vardas | Įtaisų kiekis, vnt.  | Įtaisų kaina, eur.  |
 ------------------------------------------------------------
-|  2 | Laidas | 220                  | 440,00              |
+|  2 | Laidas | 220                  | 440.00              |
 ------------------------------------------------------------
 
 ----------------------------------------------------------
@@ -45,11 +45,11 @@
 ----------------------------------------------------------
 
 ----------------------------------
-| Atrinkti įtaisai (n=1, k=1,00) |
+| Atrinkti įtaisai (n=1, k=1.00) |
 ----------------------------------
 | ID |     Vardas | Kaina        |
 ----------------------------------
-|  0 | Atsuktuvas | 0,99         |
-|  1 |    Varztas | 0,05         |
+|  0 | Atsuktuvas | 0.99         |
+|  1 |    Varztas | 0.05         |
 ----------------------------------
 
diff --git a/L3/LD_24/Code/InOutUtils.cs b/L3/LD_24/Code/InOutUtils.cs
index adab74b..df1d0b3 100644
--- a/L3/LD_24/Code/InOutUtils.cs
+++ b/L3/LD_24/Code/InOutUtils.cs
@@ -35,16 +35,16 @@ namespace LD_24.Code
         /// </summary>
         /// <param name="filename">Target file</param>
         /// <returns>A list of products</returns>
-        public static ProductList ReadProducts(string filename)
+        public static LinkedList<Product> ReadProducts(string filename)
         {
-            ProductList products = new ProductList();
+            LinkedList<Product> products = new LinkedList<Product>();
             foreach (string line in ReadLines(filename))
             {
                 string[] parts = line.Split(',');
                 string id = parts[0].Trim();
                 string name = parts[1].Trim();
                 decimal price = decimal.Parse(parts[2].Trim(), CultureInfo.InvariantCulture);
-                products.AddToEnd(new Product(id, name, price));
+                products.Add(new Product(id, name, price));
             }
             return products;
         }
@@ -54,9 +54,9 @@ namespace LD_24.Code
         /// </summary>
         /// <param name="filename">Target file</param>
         /// <returns>A list of orders</returns>
-        public static OrderList ReadOrders(string filename)
+        public static LinkedList<Order> ReadOrders(string filename)
         {
-            OrderList orders = new OrderList();
+            LinkedList<Order> orders = new LinkedList<Order>();
             foreach (string line in ReadLines(filename))
             {
                 string[] parts = line.Split(',');
@@ -64,7 +64,7 @@ namespace LD_24.Code
                 string customerName = parts[1].Trim();
                 string productID = parts[2].Trim();
                 int productAmount = int.Parse(parts[3].Trim());
-                orders.AddToEnd(new Order(customerSurname, customerName, productID, productAmount));
+                orders.Add(new Order(customerSurname, customerName, productID, productAmount));
             }
             return orders;
         }
@@ -95,11 +95,11 @@ namespace LD_24.Code
         /// <param name="list">Target list</param>
         /// <param name="columns">Column names</param>
         /// <returns>A IEnumerable for inserting values for each row</returns>
-        private static IEnumerable<Tuple<object, List<String>>> PrintTable(StreamWriter writer, string header, IEnumerable list, params string[] columns)
+        private static IEnumerable<Tuple<T, List<string>>> PrintTable<T>(StreamWriter writer, string header, IEnumerable<T> list, params string[] columns)
         {
             // 0. Collect all the rows
             List<List<string>> rows = new List<List<string>>();
-            foreach (object item in list)
+            foreach (T item in list)
             {
                 List<string> row = new List<string>();
                 yield return Tuple.Create(item, row);
@@ -167,11 +167,11 @@ namespace LD_24.Code
         /// <param name="writer">Target file</param>
         /// <param name="orders">List of orders</param>
         /// <param name="header">Header above table</param>
-        public static void PrintOrders(StreamWriter writer, OrderList orders, string header)
+        public static void PrintOrders(StreamWriter writer, IEnumerable<Order> orders, string header)
         {
             foreach (var tuple in PrintTable(writer, header, orders, "Pavardė", "Vardas", "-Įtaisas", "-Įtaiso kiekis"))
             {
-                Order order = (Order)tuple.Item1;
+                Order order = tuple.Item1;
                 List<string> row = tuple.Item2;
                 row.Add(order.CustomerSurname);
                 row.Add(order.CustomerName);
@@ -187,18 +187,18 @@ namespace LD_24.Code
         /// <param name="orders">List of orders</param>
         /// <param name="products">List of products</param>
         /// <param name="header">Header above table</param>
-        public static void PrintOrdersWithPrices(StreamWriter writer, OrderList orders, ProductList products, string header)
+        public static void PrintOrdersWithPrices(StreamWriter writer, IEnumerable<Order> orders, IEnumerable<Product> products, string header)
         {
             foreach (var tuple in PrintTable(writer, header, orders, "Pavardė", "Vardas", "-Įtaiso kiekis, vnt.", "-Kaina, eur."))
             {
-                Order order = (Order)tuple.Item1;
+                Order order = tuple.Item1;
                 List<string> row = tuple.Item2;
                 Product product = TaskUtils.FindByID(products, order.ProductID);
 
                 row.Add(order.CustomerSurname);
                 row.Add(order.CustomerName);
                 row.Add(order.ProductAmount.ToString());
-                row.Add(String.Format("{0:f2}", order.ProductAmount * product.Price));
+                row.Add(string.Format("{0:f2}", order.ProductAmount * product.Price));
             }
         }
 
@@ -208,15 +208,15 @@ namespace LD_24.Code
         /// <param name="writer">Target file</param>
         /// <param name="products">List of products</param>
         /// <param name="header">Header above table</param>
-        public static void PrintProducts(StreamWriter writer, ProductList products, string header)
+        public static void PrintProducts(StreamWriter writer, IEnumerable<Product> products, string header)
         {
             foreach (var tuple in PrintTable(writer, header, products, "ID", "Vardas", "-Kaina"))
             {
-                Product product = (Product)tuple.Item1;
+                Product product = tuple.Item1;
                 List<string> row = tuple.Item2;
                 row.Add(product.ID);
                 row.Add(product.Name);
-                row.Add(String.Format("{0:f2}", product.Price));
+                row.Add(string.Format("{0:f2}", product.Price));
             }
         }
 
@@ -227,17 +227,17 @@ namespace LD_24.Code
         /// <param name="orders">List of orders</param>
         /// <param name="popularProducts">List of most popular products</param>
         /// <param name="header">Header above table</param>
-        public static void PrintMostPopularProducts(StreamWriter writer, OrderList orders, ProductList popularProducts, string header)
+        public static void PrintMostPopularProducts(StreamWriter writer, IEnumerable<Order> orders, IEnumerable<Product> popularProducts, string header)
         {
             foreach (var tuple in PrintTable(writer, header, popularProducts, "ID", "Vardas", "-Įtaisų kiekis, vnt.", "-Įtaisų kaina, eur."))
             {
-                Product product = (Product)tuple.Item1;
+                Product product = tuple.Item1;
                 List<string> row = tuple.Item2;
                 int sales = TaskUtils.CountProductSales(orders, product.ID);
                 row.Add(product.ID);
                 row.Add(product.Name);
                 row.Add(sales.ToString());
-                row.Add(String.Format("{0:f2}", sales * product.Price));
+                row.Add(string.Format("{0:f2}", sales * product.Price));
             }
         }
     }
diff --git a/L3/LD_24/Code/LinkedList.cs b/L3/LD_24/Code/LinkedList.cs
new file mode 100644
index 0000000..4a389d5
--- /dev/null
+++ b/L3/LD_24/Code/LinkedList.cs
@@ -0,0 +1,94 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Web;
+
+namespace LD_24.Code
+{
+    public class LinkedList<T> : IEnumerable<T>
+        where T: IComparable<T>, IEquatable<T>
+    {
+        class Node
+        {
+            public T Data { get; set; }
+            public Node Next { get; set; }
+
+            public Node(T data, Node next = null)
+            {
+                Data = data;
+                Next = next;
+            }
+        }
+
+        private Node head;
+        private Node tail;
+
+        public void Add(T customer)
+        {
+            Node node = new Node(customer);
+            if (tail != null && head != null)
+            {
+                tail.Next = node;
+                tail = node;
+            }
+            else
+            {
+                tail = node;
+                head = node;
+            }
+        }
+
+        public int Count()
+        {
+            int count = 0;
+            Node current = head;
+            while (current != null)
+            {
+                current = current.Next;
+                count++;
+            }
+            return count;
+        }
+
+        public bool IsEmpty()
+        {
+            return head == null;
+        }
+
+        public void Sort()
+        {
+            for (Node nodeA = head; nodeA != null; nodeA = nodeA.Next)
+            {
+                Node min = nodeA;
+                for (Node nodeB = nodeA.Next; nodeB != null; nodeB = nodeB.Next)
+                {
+                    if (nodeB.Data.CompareTo(min.Data) > 0)
+                    {
+                        min = nodeB;
+                    }
+                }
+
+                T tmp = nodeA.Data;
+                nodeA.Data = min.Data;
+                min.Data = tmp;
+            }
+        }
+
+        public override string ToString()
+        {
+            return String.Format("LinkedList<{0}>{ Count = '{0}' }", Count());
+        }
+
+        public IEnumerator<T> GetEnumerator()
+        {
+            for (Node d = head; d != null; d = d.Next)
+                yield return d.Data;
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+    }
+}
\ No newline at end of file
diff --git a/L3/LD_24/Code/Order.cs b/L3/LD_24/Code/Order.cs
index 1931ccd..a99f300 100644
--- a/L3/LD_24/Code/Order.cs
+++ b/L3/LD_24/Code/Order.cs
@@ -8,7 +8,7 @@ namespace LD_24.Code
     /// <summary>
     /// Class used for storing a single order
     /// </summary>
-    public class Order
+    public class Order: IEquatable<Order>, IComparable<Order>
     {
         /// <summary>
         /// Surname of customer who ordered
@@ -40,38 +40,44 @@ namespace LD_24.Code
             return String.Format("Order{Name = '{0}'}", CustomerName);
         }
 
-        public static bool operator <(Order a, Order b)
+        public int CompareTo(Order other)
         {
-            if (a.ProductAmount > b.ProductAmount)
+            if (ProductAmount > other.ProductAmount)
             {
-                return true;
+                return 1;
             }
-            else if (a.ProductAmount == b.ProductAmount)
+            else if (ProductAmount == other.ProductAmount)
             {
-                int surnameCompare = a.CustomerSurname.CompareTo(b.CustomerSurname);
+                int surnameCompare = CustomerSurname.CompareTo(other.CustomerSurname);
                 if (surnameCompare < 0)
                 {
-                    return true;
+                    return 1;
                 }
-                else if (surnameCompare == 0)
+                else if (surnameCompare == 0 && CustomerName.CompareTo(other.CustomerName) < 0)
                 {
-                    return a.CustomerName.CompareTo(b.CustomerName) < 0;
+                    return 1;
                 }
             }
 
-            return false;
+            return Equals(other) ? 0 : -1;
         }
-        public static bool operator >(Order a, Order b)
+
+        public bool Equals(Order other)
         {
-            return !(a < b && a == b);
+            return CustomerSurname == other.CustomerSurname &&
+                   CustomerName == other.CustomerName &&
+                   ProductID == other.ProductID &&
+                   ProductAmount == other.ProductAmount;
         }
-        public static bool operator ==(Order a, Order b)
+
+        public override int GetHashCode()
         {
-            return a.ProductAmount == b.ProductAmount && a.CustomerName == b.CustomerName && a.CustomerSurname == b.CustomerSurname;
-        }
-        public static bool operator !=(Order a, Order b)
-        {
-            return !(a == b);
+            int hashCode = -273364163;
+            hashCode = hashCode * -1521134295 + EqualityComparer<string>.Default.GetHashCode(CustomerSurname);
+            hashCode = hashCode * -1521134295 + EqualityComparer<string>.Default.GetHashCode(CustomerName);
+            hashCode = hashCode * -1521134295 + EqualityComparer<string>.Default.GetHashCode(ProductID);
+            hashCode = hashCode * -1521134295 + ProductAmount.GetHashCode();
+            return hashCode;
         }
     }
 }
\ No newline at end of file
diff --git a/L3/LD_24/Code/OrderList.cs b/L3/LD_24/Code/OrderList.cs
deleted file mode 100644
index 9e04ab2..0000000
--- a/L3/LD_24/Code/OrderList.cs
+++ /dev/null
@@ -1,125 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
-using System.Web;
-
-namespace LD_24.Code
-{
-    /// <summary>
-    /// Stores a orders in a linked list
-    /// </summary>
-    public class OrderList : IEnumerable<Order>
-    {
-        class OrderNode
-        {
-            public Order Data { get; set; }
-            public OrderNode Next { get; set; }
-
-            public OrderNode(Order data = null, OrderNode next = null)
-            {
-                Data = data;
-                Next = next;
-            }
-        }
-
-        private OrderNode head;
-        private OrderNode tail;
-
-        /// <summary>
-        /// Append a value to the end of the linked list
-        /// </summary>
-        /// <param name="customer"></param>
-        public void AddToEnd(Order customer)
-        {
-            OrderNode node = new OrderNode(customer);
-            if (tail != null && head != null)
-            {
-                tail.Next = node;
-                tail = node;
-            }
-            else
-            {
-                tail = node;
-                head = node;
-            }
-        }
-
-        /// <summary>
-        /// Insert a value to the start of the linked list
-        /// </summary>
-        /// <param name="customer"></param>
-        public void AddToStart(Order customer)
-        {
-            OrderNode node = new OrderNode(customer);
-            if (tail != null && head != null)
-            {
-                node.Next = head;
-                head = node;
-            }
-            else
-            {
-                tail = node;
-                head = node;
-            }
-        }
-
-        /// <summary>
-        /// Get the number of values stored in linked list
-        /// </summary>
-        /// <returns>A count</returns>
-        public int Count()
-        {
-            int count = 0;
-            OrderNode current = head;
-            while (current != null)
-            {
-                current = current.Next;
-                count++;
-            }
-            return count;
-        }
-
-        /// <summary>
-        /// Sorts the linked list
-        /// </summary>
-        public void Sort()
-        {
-            for (OrderNode nodeA = head; nodeA != null; nodeA = nodeA.Next)
-            {
-                OrderNode min = nodeA;
-                for (OrderNode nodeB = nodeA.Next; nodeB != null; nodeB = nodeB.Next)
-                {
-                    if (nodeB.Data < min.Data)
-                    {
-                        min = nodeB;
-                    }
-                }
-
-                Order tmp = nodeA.Data;
-                nodeA.Data = min.Data;
-                min.Data = tmp;
-            }
-        }
-
-        public override string ToString()
-        {
-            return String.Format("OrderList{ Count = '{0}' }", Count());
-        }
-
-        public IEnumerator<Order> GetEnumerator()
-        {
-            OrderNode current = head;
-            while (current != null)
-            {
-                yield return current.Data;
-                current = current.Next;
-            }
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            return GetEnumerator();
-        }
-    }
-}
\ No newline at end of file
diff --git a/L3/LD_24/Code/Product.cs b/L3/LD_24/Code/Product.cs
index d2ad1bc..de7a900 100644
--- a/L3/LD_24/Code/Product.cs
+++ b/L3/LD_24/Code/Product.cs
@@ -8,7 +8,7 @@ namespace LD_24.Code
     /// <summary>
     /// Holds informations about a single product
     /// </summary>
-    public class Product
+    public class Product: IEquatable<Product>, IComparable<Product>
     {
         /// <summary>
         /// Identification number of product
@@ -34,5 +34,26 @@ namespace LD_24.Code
         {
             return String.Format("Product{ID = '{0}'}", ID);
         }
+
+        public bool Equals(Product other)
+        {
+            return ID == other.ID &&
+                   Name == other.Name &&
+                   Price == other.Price;
+        }
+
+        public override int GetHashCode()
+        {
+            int hashCode = 560300832;
+            hashCode = hashCode * -1521134295 + EqualityComparer<string>.Default.GetHashCode(ID);
+            hashCode = hashCode * -1521134295 + EqualityComparer<string>.Default.GetHashCode(Name);
+            hashCode = hashCode * -1521134295 + Price.GetHashCode();
+            return hashCode;
+        }
+
+        public int CompareTo(Product other)
+        {
+            return ID.CompareTo(other.ID);
+        }
     }
 }
diff --git a/L3/LD_24/Code/ProductList.cs b/L3/LD_24/Code/ProductList.cs
deleted file mode 100644
index db56384..0000000
--- a/L3/LD_24/Code/ProductList.cs
+++ /dev/null
@@ -1,103 +0,0 @@
-using System;
-using System.Collections;
-using System.Collections.Generic;
-using System.Linq;
-using System.Web;
-
-namespace LD_24.Code
-{
-    /// <summary>
-    /// Stores multiple products in a linked list
-    /// </summary>
-    public class ProductList : IEnumerable<Product>
-    {
-        class ProductNode
-        {
-            public Product Data { get; set; }
-            public ProductNode Next { get; set; }
-
-            public ProductNode(Product data = null, ProductNode next = null)
-            {
-                Data = data;
-                Next = next;
-            }
-        }
-
-        private ProductNode head;
-        private ProductNode tail;
-
-        /// <summary>
-        /// Append a value to the end of the linked list
-        /// </summary>
-        /// <param name="product"></param>
-        public void AddToEnd(Product product)
-        {
-            ProductNode node = new ProductNode(product);
-            if (tail != null && head != null)
-            {
-                tail.Next = node;
-                tail = node;
-            }
-            else
-            {
-                tail = node;
-                head = node;
-            }
-        }
-
-        /// <summary>
-        /// Inserts a value to the start of the linked list
-        /// </summary>
-        /// <param name="product"></param>
-        public void AddToStart(Product product)
-        {
-            ProductNode node = new ProductNode(product);
-            if (tail != null && head != null)
-            {
-                node.Next = head;
-                head = node;
-            }
-            else
-            {
-                tail = node;
-                head = node;
-            }
-        }
-
-        /// <summary>
-        /// Get the number of values stored in the linked list
-        /// </summary>
-        /// <returns>A count</returns>
-        public int Count()
-        {
-            int count = 0;
-            ProductNode current = head;
-            while (current != null)
-            {
-                current = current.Next;
-                count++;
-            }
-            return count;
-        }
-
-        public override string ToString()
-        {
-            return String.Format("ProductList{ Count = '{0}' }", Count());
-        }
-
-        public IEnumerator<Product> GetEnumerator()
-        {
-            ProductNode current = head;
-            while (current != null)
-            {
-                yield return current.Data;
-                current = current.Next;
-            }
-        }
-
-        IEnumerator IEnumerable.GetEnumerator()
-        {
-            return GetEnumerator();
-        }
-    }
-}
\ No newline at end of file
diff --git a/L3/LD_24/Code/TaskUtils.cs b/L3/LD_24/Code/TaskUtils.cs
index 41262fe..cd7c7e9 100644
--- a/L3/LD_24/Code/TaskUtils.cs
+++ b/L3/LD_24/Code/TaskUtils.cs
@@ -16,7 +16,7 @@ namespace LD_24.Code
         /// </summary>
         /// <param name="orders">List of orders</param>
         /// <returns>List of products ids</returns>
-        public static List<string> FindMostPopularProducts(OrderList orders)
+        public static List<string> FindMostPopularProducts(IEnumerable<Order> orders)
         {
             Dictionary<string, int> productSales = new Dictionary<string, int>();
             foreach (Order order in orders)
@@ -55,7 +55,7 @@ namespace LD_24.Code
         /// <param name="orders">List of products</param>
         /// <param name="product">Target product id</param>
         /// <returns>Sales</returns>
-        public static int CountProductSales(OrderList orders, string product)
+        public static int CountProductSales(IEnumerable<Order> orders, string product)
         {
             int sales = 0;
             foreach (Order order in orders)
@@ -73,7 +73,7 @@ namespace LD_24.Code
         /// </summary>
         /// <param name="orders">A list of orders</param>
         /// <returns>A list of orders where same orders have been merged</returns>
-        public static OrderList MergeOrders(OrderList orders)
+        public static LinkedList<Order> MergeOrders(IEnumerable<Order> orders)
         {
             Dictionary<Tuple<string, string, string>, Order> ordersByName = new Dictionary<Tuple<string, string, string>, Order>();
             foreach (var order in orders)
@@ -88,10 +88,10 @@ namespace LD_24.Code
                 }
             }
 
-            OrderList mergedOrders = new OrderList();
+            LinkedList<Order> mergedOrders = new LinkedList<Order>();
             foreach (var order in ordersByName.Values)
             {
-                mergedOrders.AddToEnd(order);
+                mergedOrders.Add(order);
             }
             return mergedOrders;
         }
@@ -102,7 +102,7 @@ namespace LD_24.Code
         /// <param name="products">List of products</param>
         /// <param name="id">Target product id</param>
         /// <returns>The product</returns>
-        public static Product FindByID(ProductList products, string id)
+        public static Product FindByID(IEnumerable<Product> products, string id)
         {
             foreach (Product product in products)
             {
@@ -120,12 +120,12 @@ namespace LD_24.Code
         /// <param name="products">List of products</param>
         /// <param name="ids">List of product ids</param>
         /// <returns>List of products</returns>
-        public static ProductList FindByID(ProductList products, List<string> ids)
+        public static LinkedList<Product> FindByID(IEnumerable<Product> products, List<string> ids)
         {
-            ProductList foundProducts = new ProductList();
+            LinkedList<Product> foundProducts = new LinkedList<Product>();
             foreach (string id in ids)
             {
-                foundProducts.AddToEnd(FindByID(products, id));
+                foundProducts.Add(FindByID(products, id));
             }
             return foundProducts;
         }
@@ -138,9 +138,9 @@ namespace LD_24.Code
         /// <param name="minSold">Minimmum sales amount</param>
         /// <param name="maxPrice">Max product price</param>
         /// <returns>A list of filtered products</returns>
-        public static ProductList FilterByQuantitySoldAndPrice(ProductList products, OrderList orders, int minSold, decimal maxPrice)
+        public static LinkedList<Product> FilterByQuantitySoldAndPrice(IEnumerable<Product> products, IEnumerable<Order> orders, int minSold, decimal maxPrice)
         {
-            ProductList filtered = new ProductList();
+            LinkedList<Product> filtered = new LinkedList<Product>();
             foreach (Product product in products)
             {
                 if (product.Price < maxPrice)
@@ -148,7 +148,7 @@ namespace LD_24.Code
                     int sold = CountProductSales(orders, product.ID);
                     if (sold >= minSold)
                     {
-                        filtered.AddToEnd(product);
+                        filtered.Add(product);
                     }
                 }
             }
@@ -160,25 +160,25 @@ namespace LD_24.Code
         /// </summary>
         /// <param name="orders">List of orders</param>
         /// <returns>A list of filtered orders</returns>
-        public static OrderList FindCustomerWithSingleProduct(OrderList orders)
+        public static LinkedList<Order> FindCustomerWithSingleProduct(IEnumerable<Order> orders)
         {
-            Dictionary<Tuple<string, string>, OrderList> ordersByCusomer = new Dictionary<Tuple<string, string>, OrderList>(); 
-            foreach (var order in TaskUtils.MergeOrders(orders))
+            var ordersByCusomer = new Dictionary<Tuple<string, string>, LinkedList<Order>>(); 
+            foreach (var order in MergeOrders(orders))
             {
                 var key = Tuple.Create(order.CustomerName, order.CustomerSurname);
                 if (!ordersByCusomer.ContainsKey(key))
                 {
-                    ordersByCusomer.Add(key, new OrderList());
+                    ordersByCusomer.Add(key, new LinkedList<Order>());
                 }
-                ordersByCusomer[key].AddToEnd(order);
+                ordersByCusomer[key].Add(order);
             }
 
-            OrderList finalList = new OrderList();
+            LinkedList<Order> finalList = new LinkedList<Order>();
             foreach (var customerOrders in ordersByCusomer.Values)
             {
                 if (customerOrders.Count() == 1)
                 {
-                    finalList.AddToEnd(customerOrders.First());
+                    finalList.Add(customerOrders.First());
                 }
             }
             return finalList;
diff --git a/L3/LD_24/Forma1.aspx.cs b/L3/LD_24/Forma1.aspx.cs
index f9ee37a..cdb7ab7 100644
--- a/L3/LD_24/Forma1.aspx.cs
+++ b/L3/LD_24/Forma1.aspx.cs
@@ -30,13 +30,13 @@ namespace LD_24
 
             FindControl("ResultsDiv").Visible = true;
 
-            ProductList products = InOutUtils.ReadProducts(Server.MapPath(inputFileA));
-            OrderList orders = InOutUtils.ReadOrders(Server.MapPath(inputFileB));
+            var products = InOutUtils.ReadProducts(Server.MapPath(inputFileA));
+            var orders = InOutUtils.ReadOrders(Server.MapPath(inputFileB));
 
             List<string> mostPopularProductIds = TaskUtils.FindMostPopularProducts(orders);
-            ProductList mostPopularProducts = TaskUtils.FindByID(products, mostPopularProductIds);
-            ProductList filteredProducts = TaskUtils.FilterByQuantitySoldAndPrice(products, orders, n, k);
-            OrderList customersWithSingleProduct = TaskUtils.FindCustomerWithSingleProduct(orders);
+            var mostPopularProducts = TaskUtils.FindByID(products, mostPopularProductIds);
+            var filteredProducts = TaskUtils.FilterByQuantitySoldAndPrice(products, orders, n, k);
+            var customersWithSingleProduct = TaskUtils.FindCustomerWithSingleProduct(orders);
             customersWithSingleProduct.Sort();
 
             ShowProducts(Table1, products);
diff --git a/L3/LD_24/Forma1Utils.aspx.cs b/L3/LD_24/Forma1Utils.aspx.cs
index f36f09e..c91d3cf 100644
--- a/L3/LD_24/Forma1Utils.aspx.cs
+++ b/L3/LD_24/Forma1Utils.aspx.cs
@@ -18,7 +18,7 @@ namespace LD_24
         /// <param name="list">Target list</param>
         /// <param name="columns">Columns names</param>
         /// <returns></returns>
-        private IEnumerable<Tuple<object, TableRow>> ShowTable(Table table, IEnumerable list, params string[] columns)
+        private IEnumerable<Tuple<T, TableRow>> ShowTable<T>(Table table, IEnumerable<T> list, params string[] columns)
         {
             TableRow header = new TableRow();
             foreach (string column in columns)
@@ -28,7 +28,7 @@ namespace LD_24
             table.Rows.Add(header);
 
             int n = 0;
-            foreach (object item in list)
+            foreach (T item in list)
             {
                 TableRow row = new TableRow();
                 yield return Tuple.Create(item, row);
@@ -49,11 +49,11 @@ namespace LD_24
         /// </summary>
         /// <param name="table">Target table</param>
         /// <param name="products">Target products</param>
-        public void ShowProducts(Table table, ProductList products)
+        public void ShowProducts(Table table, IEnumerable<Product> products)
         {
             foreach (var tuple in ShowTable(table, products, "ID", "Vardas", "Kaina, eur."))
             {
-                Product product = (Product)tuple.Item1;
+                Product product = tuple.Item1;
                 TableRow row = tuple.Item2;
                 row.Cells.Add(new TableCell { Text = product.ID });
                 row.Cells.Add(new TableCell { Text = product.Name });
@@ -66,11 +66,11 @@ namespace LD_24
         /// </summary>
         /// <param name="table">Target table</param>
         /// <param name="orders">Target orders</param>
-        public void ShowOrders(Table table, OrderList orders)
+        public void ShowOrders(Table table, IEnumerable<Order> orders)
         {
             foreach (var tuple in ShowTable(table, orders, "Pavardė", "Vardas", "Įtaisas", "Įtaisų kiekis, vnt."))
             {
-                Order order = (Order)tuple.Item1;
+                Order order = tuple.Item1;
                 TableRow row = tuple.Item2;
                 row.Cells.Add(new TableCell { Text = order.CustomerSurname });
                 row.Cells.Add(new TableCell { Text = order.CustomerName });
@@ -85,17 +85,17 @@ namespace LD_24
         /// <param name="table">Target table</param>
         /// <param name="orders">Target orders</param>
         /// <param name="popularProducts">List of most popular products</param>
-        public void ShowMostPopularProducts(Table table, OrderList orders, ProductList popularProducts)
+        public void ShowMostPopularProducts(Table table, IEnumerable<Order> orders, IEnumerable<Product> popularProducts)
         {
             foreach (var tuple in ShowTable(table, popularProducts, "ID", "Vardas", "Įtaisų kiekis, vnt.", "Įtaisų kaina, eur."))
             {
-                Product product = (Product)tuple.Item1;
+                Product product = tuple.Item1;
                 TableRow row = tuple.Item2;
                 int sales = TaskUtils.CountProductSales(orders, product.ID);
                 row.Cells.Add(new TableCell { Text = product.ID });
                 row.Cells.Add(new TableCell { Text = product.Name });
                 row.Cells.Add(new TableCell { Text = sales.ToString() });
-                row.Cells.Add(new TableCell { Text = String.Format("{0:f2}", sales * product.Price) });
+                row.Cells.Add(new TableCell { Text = string.Format("{0:f2}", sales * product.Price) });
             }
         }
 
@@ -105,18 +105,18 @@ namespace LD_24
         /// <param name="table">Target table</param>
         /// <param name="orders">Target orders</param>
         /// <param name="products">List of products</param>
-        public void ShowOrdersWithPrices(Table table, OrderList orders, ProductList products)
+        public void ShowOrdersWithPrices(Table table, IEnumerable<Order> orders, IEnumerable<Product> products)
         {
             foreach (var tuple in ShowTable(table, orders, "Pavardė", "Vardas", "Įtaisų kiekis, vnt.", "Sumokėta, eur."))
             {
-                Order order = (Order)tuple.Item1;
+                Order order = tuple.Item1;
                 TableRow row = tuple.Item2;
                 Product product = TaskUtils.FindByID(products, order.ProductID);
 
                 row.Cells.Add(new TableCell { Text = order.CustomerSurname });
                 row.Cells.Add(new TableCell { Text = order.CustomerName });
                 row.Cells.Add(new TableCell { Text = order.ProductAmount.ToString() });
-                row.Cells.Add(new TableCell { Text = String.Format("{0:f2}", order.ProductAmount * product.Price, 2) });
+                row.Cells.Add(new TableCell { Text = string.Format("{0:f2}", order.ProductAmount * product.Price, 2) });
             }
         }
     }
diff --git a/L3/LD_24/LD_24.csproj b/L3/LD_24/LD_24.csproj
index 60273d9..20d63f1 100644
--- a/L3/LD_24/LD_24.csproj
+++ b/L3/LD_24/LD_24.csproj
@@ -106,10 +106,9 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="Code\InOutUtils.cs" />
+    <Compile Include="Code\LinkedList.cs" />
     <Compile Include="Code\Order.cs" />
-    <Compile Include="Code\OrderList.cs" />
     <Compile Include="Code\Product.cs" />
-    <Compile Include="Code\ProductList.cs" />
     <Compile Include="Code\TaskUtils.cs" />
     <Compile Include="Forma1.aspx.cs">
       <DependentUpon>Forma1.aspx</DependentUpon>