using System;

using System.Linq;

using System.Collections.Generic;

​

namespace MergeTask

{

    public class MergeClass

    {

​

        private readonly record struct ItemData(string id, int level);

        private static void Merge(List<ItemData> field)

        {

            // Write your code here

        }

        // =============================================================================

        // =================================== TESTS ===================================

        // =============================================================================

        // =============================================================================

        // =============================================================================

        public static void Main(string[] args)

        {

            try {

                Test1();

                Test2();

                Test3();

                Test4();

                Test5();

                Console.WriteLine("Success!");

            } catch {}

        }

​

        private static void Test1()

        {

            var field = new List<ItemData>{ new("apple", 1), new("apple", 1) };

            Merge(field);

            Assert(field, new List<ItemData> { new("apple", 2) });

        }

​

        private static void Test2()

        {

            var field = new List<ItemData>

            {

                new("apple", 1), 

                new("apple", 1),

                new("home", 1),

                new("home", 2),

                new("home", 1),

                new("apple", 1),

            };

            Merge(field);

            Assert(field, new List<ItemData>

            {

                new("apple", 2),

                new("apple", 1),

                new("home", 3),

            });

        }

        private static void Test3()

        {

            var field = Enumerable.Repeat(new ItemData("abc", 1), 256).ToList();

            Merge(field);

            Assert(field, new List<ItemData>

            {

                new("abc", 9),

            });

        }

        private static void Test4()

        {

            var field = Enumerable.Repeat(new ItemData("abc", 1), 260).ToList();

            Merge(field);

            Assert(field, new List<ItemData>

            {

                new("abc", 9),

                new("abc", 3),

            });

        }

        private static void Test5()

        {

            var field = 

                    Enumerable.Repeat(new ItemData("abc", 1), 260)

                    .Concat(new ItemData []

                    {

                        new("apple", 1), 

                        new("apple", 1),

                        new("home", 1),

                        new("home", 2),

                        new("home", 1),

                        new("apple", 1),

                    })

                    .Concat(Enumerable.Repeat(new ItemData("eee", 1), 100)).ToList();

            Merge(field);

            Assert(field, new List<ItemData>

            {

                new("abc", 9),

                new("abc", 3),

                new("apple", 2),

                new("apple", 1),

                new("home", 3),

                new("eee", 7),

                new("eee", 6),

                new("eee", 3)

            });

        }

​

        private static void Assert(List<ItemData> actual, List<ItemData> expected)

        {

            if (actual.Except(expected).Any() || expected.Except(actual).Any())

            {

                Console.WriteLine($"Actual: {string.Join(", ", actual)}");

                Console.WriteLine($"Expected: {string.Join(", ", expected)}");

                throw new Exception("Test failed");

            }

        }

    }

}