EmptyInsideTriangle

using System;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            for (int i = 0; i < n; i++)
            {
                for (int j = 0; j <= i; j++)
                {
                    if (j == 0 || j == i || i == n - 1)
                    {
                        Console.Write("*");
                    }
                    else
                    {
                        Console.Write(" ");
                    }
                }
                Console.WriteLine();
            }
        }
    }
}