diff --git a/Makefile b/Makefile
index d36c479..debe64b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CFLAGS=-lm -g -Wall -Walloc-size-larger-than=-1
+CFLAGS=-lm -g -Wall
 
 .PHONY := gen_data main
 
@@ -7,11 +7,11 @@ main: build/main
 
 build/gen_data: src/gen_data.c
 	mkdir -p build
-	gcc -o build/gen_data src/gen_data.c $(CFLAGS) -O2
+	gcc -o build/gen_data src/gen_data.c $(CFLAGS) -O0
 
 build/main: src/main.c src/json_parser.c
 	mkdir -p build
-	gcc -o build/main src/main.c $(CFLAGS) -O2
+	gcc -o build/main src/main.c $(CFLAGS) -O0
 
 clean:
 	rm -r build
diff --git a/README.md b/README.md
index fe67957..feb636c 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,5 @@
 # Harvensine computing
 
 For [Computer, Enhance!](https://www.computerenhance.com/)
+
+Json spec: https://www.json.org/json-en.html
diff --git a/src/gen_data.c b/src/gen_data.c
index 2002269..ff83de4 100644
--- a/src/gen_data.c
+++ b/src/gen_data.c
@@ -139,6 +139,13 @@ static void print_usage(char *program) {
     fprintf(stderr, "\tcluster <size> <json-output-file> [seed]\n");
 }
 
+u64 get_current_time_us()
+{
+	struct timespec time;
+	clock_gettime(CLOCK_MONOTONIC_RAW, &time);
+	return time.tv_sec * 1000000 + time.tv_nsec / 1000;
+}
+
 int main(int argc, char **argv) {
     if (argc < 2) {
         print_usage(argv[0]);
@@ -197,6 +204,7 @@ int main(int argc, char **argv) {
         return -1;
     }
 
+	u64 start_time = get_current_time_us();
     srand(seed);
     f64 sum = 0;
     if (method == GEN_UNIFORM) {
@@ -246,11 +254,13 @@ int main(int argc, char **argv) {
     }
 
     fwrite(&sum, sizeof(f64), 1, answer_file);
+	u64 duration = get_current_time_us() - start_time;
 
     printf("Used earth radius: %f\n", EARTH_RADIUS);
     printf("Seed: %d\n", seed);
     printf("Number of pairs: %d\n", row_count);
     printf("Expected sum: %lf\n", sum);
+    printf("Duration: %ldus (%lfus/row)\n", duration, ((f64)duration) / row_count);
 
     return 0;
-}
\ No newline at end of file
+}
diff --git a/src/json_parser.c b/src/json_parser.c
index d8aa853..422dcaf 100644
--- a/src/json_parser.c
+++ b/src/json_parser.c
@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <assert.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "json_parser.h"
 
@@ -339,6 +340,18 @@ int parse_json_bool(bool *result, char *data, size_t data_size)
 	return 0; // TODO:
 }
 
+struct json_value *get_json_object_value(struct json_object *obj, char *key, size_t key_size)
+{
+	for (int i = 0; i < obj->count; i++)
+	{
+		struct json_string *obj_key = obj->keys[i];
+		if (obj_key->size == key_size && !strncmp(obj_key->str, key, key_size)) {
+			return obj->values[i];
+		}
+	}
+	return NULL;
+}
+
 
 void printf_json_array(struct json_array *array)
 {
diff --git a/src/json_parser.h b/src/json_parser.h
index de2ec70..1d34457 100644
--- a/src/json_parser.h
+++ b/src/json_parser.h
@@ -56,3 +56,5 @@ void printf_json_value(struct json_value *result);
 void printf_json_string(struct json_string *string);
 void printf_json_object(struct json_object *object);
 void printf_json_array(struct json_array *array);
+
+struct json_value *get_json_object_value(struct json_object *obj, char *key, size_t key_size);
diff --git a/src/main.c b/src/main.c
index 72ea432..2947831 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,12 +1,33 @@
+#include <assert.h>
 #include <stdio.h>
 #include <inttypes.h>
-#include <inttypes.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <math.h>
 
 #include "json_parser.c"
 
+#define EARTH_RADIUS 6372.8
+
+typedef uint32_t u32;
+typedef uint64_t u64;
+
+struct point_pair {
+	f64 x0;
+	f64 y0;
+	f64 x1;
+	f64 y1;
+};
+
+struct point_pairs {
+	struct point_pair *pairs;
+	size_t count;
+};
+
 void print_usage(char *program)
 {
-	printf("Usage: %s <json-file> [test-bin-file]\n", program);
+	printf("Usage: %s <json-file> [reference-bin-file]\n", program);
 }
 
 size_t get_file_size(FILE *f)
@@ -17,9 +38,89 @@ size_t get_file_size(FILE *f)
 	return size;
 }
 
+u64 get_current_time_us()
+{
+	struct timespec time;
+	clock_gettime(CLOCK_MONOTONIC_RAW, &time);
+	return time.tv_sec * 1000000 + time.tv_nsec / 1000;
+}
+
+static f64 sqaure_f64(f64 num)
+{
+    return num*num;
+}
+
+static f64 radians_to_degrees(f64 degrees)
+{
+    return 0.01745329251994329577 * degrees;
+}
+
+static f64 get_harvensine_distance(f64 X0, f64 Y0, f64 X1, f64 Y1, f64 earth_radius)
+{
+    f64 lat1 = Y0;
+    f64 lat2 = Y1;
+    f64 lon1 = X0;
+    f64 lon2 = X1;
+
+    f64 dLat = radians_to_degrees(lat2 - lat1);
+    f64 dLon = radians_to_degrees(lon2 - lon1);
+    lat1 = radians_to_degrees(lat1);
+    lat2 = radians_to_degrees(lat2);
+
+    f64 a = sqaure_f64(sin(dLat/2.0)) + cos(lat1)*cos(lat2)*sqaure_f64(sin(dLon/2));
+    f64 c = 2.0*asin(sqrt(a));
+
+    return earth_radius * c;
+}
+
+static struct point_pairs *convert_to_struct(struct json_value *json)
+{
+	assert(json->type == JSON_TYPE_OBJECT);
+	assert(json->object->count == 1);
+	assert(!strncmp(json->object->keys[0]->str, "pairs", sizeof("pairs")-1));
+	assert(json->object->values[0]->type == JSON_TYPE_ARRAY);
+	struct json_array *pairs_array = json->object->values[0]->array;
+
+	struct point_pairs *result = malloc(sizeof(struct point_pairs));
+	result->pairs = malloc(pairs_array->count * sizeof(struct point_pair));
+	result->count = pairs_array->count;
+
+	for (int i = 0; i < result->count; i++)
+	{
+		assert(pairs_array->values[i]->type == JSON_TYPE_OBJECT);
+		assert(pairs_array->values[i]->object->count == 4);
+
+		struct json_object *json_pair = pairs_array->values[i]->object;
+		struct json_value *x0 = get_json_object_value(json_pair, "x0", sizeof("x0")-1);
+		assert(x0 != NULL && x0->type == JSON_TYPE_NUMBER);
+		struct json_value *y0 = get_json_object_value(json_pair, "y0", sizeof("y0")-1);
+		assert(y0 != NULL && y0->type == JSON_TYPE_NUMBER);
+		struct json_value *x1 = get_json_object_value(json_pair, "x1", sizeof("x1")-1);
+		assert(x1 != NULL && x1->type == JSON_TYPE_NUMBER);
+		struct json_value *y1 = get_json_object_value(json_pair, "y1", sizeof("y1")-1);
+		assert(y1 != NULL && y1->type == JSON_TYPE_NUMBER);
+
+		struct point_pair *pair = &result->pairs[i];
+		pair->x0 = x0->number;
+		pair->y0 = y0->number;
+		pair->x1 = x1->number;
+		pair->y1 = y1->number;
+
+	}
+
+	return result;
+}
+
+static void free_point_pairs(struct point_pairs *pairs)
+{
+	if (pairs == NULL)  return;
+	free(pairs->pairs);
+	free(pairs);
+}
+
 int main(int argc, char **argv)
 {
-	if (argc < 2) {
+	if (argc <= 1) {
 		print_usage(argv[0]);
 		return -1;
 	}
@@ -41,13 +142,90 @@ int main(int argc, char **argv)
 	}
 	fclose(f);
 
-	struct json_value *parsed = malloc(sizeof(struct json_value));
-	int bytes_parsed = parse_json_value(parsed, json_data, json_size);
+	f64 *reference_harvensines = NULL;
+	size_t reference_harvensines_count = 0;
+	f64 reference_harvensine_sum = 0;
+	if (argc >= 3)
+	{
+		char *answers_filename = argv[2];
+		FILE *f = fopen(answers_filename, "r");
+		if (f == NULL) {
+			printf("Failed to open: %s\n", json_filename);
+			return -1;
+		}
+		size_t file_size = get_file_size(f);
+		assert(file_size % sizeof(f64) == 0);
+		reference_harvensines_count = file_size / sizeof(f64) - 1;
+		reference_harvensines = malloc(reference_harvensines_count * sizeof(f64));
+		for (int i = 0; i < reference_harvensines_count; i++) {
+			fread(&reference_harvensines[i], sizeof(f64), 1, f);
+		}
+		fread(&reference_harvensine_sum, sizeof(f64), 1, f);
 
-	printf_json_value(parsed);
-	printf("\n");
+		fclose(f);
+	}
 
+	// Step 1. Read json file
+
+	u64 json_parse_duration;
+	struct json_value *parsed = NULL;
+	{
+		parsed = malloc(sizeof(struct json_value));
+		u64 start_time = get_current_time_us();
+		int bytes_parsed = parse_json_value(parsed, json_data, json_size);
+		assert(bytes_parsed >= 0);
+		json_parse_duration = get_current_time_us() - start_time;
+	}
+
+	u32 row_count = parsed->object->values[0]->array->count;
+	if (reference_harvensines_count > 0) {
+		assert(row_count == reference_harvensines_count);
+	}
+
+	printf("Row count: %d\n", row_count);
+	printf("Time to parse JSON: %ldus (%.3lfus/row)\n", json_parse_duration, (f64)json_parse_duration / row_count);
+
+	// Step 2. Convert json object to struct
+
+	u64 struct_convert_duration;
+	struct point_pairs *pairs = NULL;
+	{
+		u64 start_time = get_current_time_us();
+		pairs = convert_to_struct(parsed);
+		struct_convert_duration = get_current_time_us() - start_time;
+	}
+
+	printf("Time to convert to struct: %ldus (%.3lfus/row)\n", struct_convert_duration, (f64)struct_convert_duration / row_count);
+
+	// Step 3. Calculate harvensine distances
+
+	f64 *harvensines = malloc(pairs->count*sizeof(f64));
+	u64 harvensine_duration;
+	{
+		u64 start_time = get_current_time_us();
+		for (int i = 0; i < pairs->count; i++) {
+			struct point_pair *p = &pairs->pairs[i];
+			harvensines[i] = get_harvensine_distance(p->x0, p->y0, p->x1, p->y1, EARTH_RADIUS);
+		}
+		harvensine_duration = get_current_time_us() - start_time;
+	}
+
+	f64 harvensine_sum = 0;
+	for (int i = 0; i < pairs->count; i++) {
+		harvensine_sum += harvensines[i];
+	}
+
+	printf("Time to calc harvensine: %ldus (%.3lfus/row)\n", harvensine_duration, (f64)harvensine_duration / row_count);
+	printf("Sum of all harvensines: %.16f\n", harvensine_sum);
+
+	if (reference_harvensines_count > 0) {
+		printf("Diff of reference harvensine sum: %.16f\n", harvensine_sum - reference_harvensine_sum);
+	}
+
+	free(reference_harvensines);
+	free(harvensines);
 	free_json_value(parsed);
+	free_point_pairs(pairs);
 
 	return 0;
 }