12_Matrix

using System;

/*
 * 12. Write a program that reads from the console a positive integer
 * number N (N < 20) and outputs a matrix.
 */
class Matrix
{
    static void Main()
    {
        uint n;

        Console.Write("N = ");
        string strN = Console.ReadLine();

        if (!uint.TryParse(strN, out n))
        {
            Console.WriteLine("Invalid number: {0}", strN);
        }
        else
        {
            if (n < 20)
            {
                for (int i = 1; i <= n; i++)
                {
                    for (int j = i; j <= i + n - 1; j++)
                    {
                        Console.Write(Convert.ToString(j).PadLeft(3, ' '), j);
                    }

                    Console.WriteLine();
                }
            }
            else
            {
                Console.WriteLine("The entered number must be less than 20!");
            }
        }
    }
}