public static void Main()
int n = Convert.ToInt32(Console.ReadLine());
for (int row = 0; row < n; row++)
for (int col = 0; col < n; col++)
if (row == 0 && col == 0 || row == 0 && col == (n-1) ||
row == (n-1) && col == 0 || row == (n-1) && col == (n-1))
else if (col == 0 || col == (n-1))