using System;

using System.Threading.Tasks;

using System.Runtime.CompilerServices;

​

class MyAwaitable

{

    public MyAwaiter GetAwaiter()

    {

        return new MyAwaiter();

    }

    public class MyAwaiter : INotifyCompletion

    {

        public bool IsCompleted { get; }

        public void GetResult()

        {

        }

        public void OnCompleted(Action continuation)

        {

            continuation();

        }

    }

}

​

​

​

class Program

{

    static async Task Main()

    {

        for (int i = 0; i < 99999; ++i)

            await new MyAwaitable();

    }

}

​