using System;

using System.Collections.Generic;       

using System.Threading.Tasks;

​

public class Program

{

    public  static void Main()

    {

        MainAsync().ConfigureAwait(false);

    }

    public async static Task MainAsync()

    {

        await foreach (var l in FizzBuzz(15))

        {

            Console.WriteLine(l);

        }   

    }

    public static async IAsyncEnumerable<string> FizzBuzz(int n)

    {

        for (int i = 1; i <= n; i++) 

        {

            string item = (i % 3 == 0, i % 5 == 0) switch {

                (true, true) => "FizzBuzz",

                (true, false) => "Fizz",

                (false, true) => "Buzz",

                (false, false) => i.ToString()

            };

            yield return item;

        }

    }

}