using System;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    async static Task Foo()

    {

        await Task.Run(() => {

            Console.WriteLine("task start");

            Thread.Sleep(1000);

            Console.WriteLine("task finish");

        });

    }

    public static void Main()

    {

        Console.WriteLine("hi");

        var task = Foo();

        Console.WriteLine("bye");

    }

}