using System;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        int _value = 0;

        ProcessValues();

        void ProcessValues()

        {

            var updateOne = Task.Run(() => UpdateValue(1000000, 1));

            var updateTwo = Task.Run(() => UpdateValue(1000000, -1));

            var updateThree = Task.Run(() => UpdateValue(1000000, 1));

​

            Task.WaitAll(updateOne, updateTwo, updateThree);

​

            Console.WriteLine($"Value: {_value}");

        }

        void UpdateValue(int maxLoops, int amount)

        {

            for (var i = 0; i < maxLoops; i++)

            {

                _value += amount;

            }

        }

    }

}