using System;

public class Program

{

    public static void Main()

    {

        int n=5;

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

            {

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

                {

                    Console.Write(" ");

                }

                for (int k = 1; k < i * 2; k++)

                {

                    Console.Write("*");

                }

                Console.WriteLine();

            }         

            for (int i = n - 1; i >= 1; i--)

            {

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

                {

                    Console.Write(" ");

                }

                for (int k = 1; k < i * 2; k++)

                {

                    Console.Write("*");

                }

                Console.WriteLine();

            }

            Console.WriteLine();

    }

}

​