using System;

using System.Diagnostics;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        Stopwatch st = new Stopwatch();

            st.Start();

            Program p = new Program();

            var counter = Task.Run(() => p.TestAsync()).Result;

            Console.WriteLine("Counter : " + counter);

            st.Stop();

            Console.WriteLine("Total Sec : " + st.ElapsedMilliseconds.ToString());

            Console.ReadLine();

    }

    public async Task<int> TestAsync()

        {

            int total = 1;

            for (int k = 15; k <= 20; k++)

            {

                var result =await Task.Run(()=> GetLongRunningTask("Hello " + k));

                total = +5;

                Console.WriteLine(result);

            }

            return total;

        }

​

        public string GetLongRunningTask(string input)

        {

            // replaced code with for loop to make it simple.

            for(int i=0;i<= 10; i++)

            {

                Console.WriteLine(input + "__"+i);

            }

​

            for (int z = 0; z < 10; z++)

            {

                Thread.Sleep(10);

            }

            return input;

        }

}