using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Please enter a number:");

        // assuming that the user will put int only, i will not the validation for making things simple

        var number=Convert.ToInt32(Console.ReadLine());

        for(int i=0; i < number; i++)

        {           

            for(int j=0; j < number; j++)

            {           

                if(i==0 || i == number-1 || j==0 || j == number-1)

                    Console.Write("* "); // adding * and space to make the horizontal and vertical widths almost the same,

                                         //to know more, try to remove the spaces and let the number = 25, result will be sides not equal in visual display

                else 

                    Console.Write("  "); // adding 2 spaces instead of one to let the horizontal and veritcal widths almost the same

            }

            Console.Write("\n");

        }

    }

}