using System;
using System.Threading.Tasks;
class Program
{
    static void Main(string[] args)
    {
        var t = Task.Run(() => DoAsync());
        t.Wait();
    }

    private static async Task DoAsync()
    {
        for (int i = 5; i > 0; i--)
        {
            Console.WriteLine($"{i}...");
            await Task.Delay(1000);
        }
    }
}