using System;

public class Program

{

    public static void Main()

    {

            Console.WriteLine("Enter the size of the frame:");

            int size = int.Parse(Console.ReadLine());

​

​

            Console.Write("+");

            for (int i = 0; i < size - 2; i++)

            {

                Console.Write("-");

            }

            Console.WriteLine("+");

​

            for (int i = 0; i < size - 2; i++)

            {

                Console.Write("|");

                for (int j = 0; j < size - 2; j++)

                {

                    Console.Write(" ");

                }

                Console.WriteLine("|");

            }

​

            Console.Write("+");

            for (int i = 0; i < size - 2; i++)

            {

                Console.Write("-");

            }

            Console.WriteLine("+");

    }

}