using System;

using System.Globalization;

using System.IO; // include the System.IO namespace

using System.Net.Http;

​

public class Program

{

    public async static void Main()

    {       

        for(int i=0;i<=3;i++){

            for (int j=0; j<i;j++){

                Console.Write("*");

            }

            Console.Write("\n");

        }

        for(int k=0;k<=3;k++){

            for (int l=2; l>k;l--){

                Console.Write("*");

            }

            Console.Write("\n");

        }

    }

}

​