using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Enter the number of the month: ");

        int month = 0;

        while(!(int.TryParse(Console.ReadLine(), out month))) Console.Write("invalid input");

        switch(month){

            case 1:

                Console.WriteLine("31 days");

                break;

            case 2:

                Console.WriteLine("28 days");

                break;

            case 3:

                Console.WriteLine("31 days");

                break;

            case 4:

                Console.WriteLine("30 days");

                break;

            case 5:

                Console.WriteLine("31 days");

                break;

            case 6:

                Console.WriteLine("30 days");

                break;

            case 7:

                Console.WriteLine("31 days");

                break;

            case 8:

                Console.WriteLine("31 days");

                break;

            case 9:

                Console.WriteLine("30 days");

                break;

            case 10:

                Console.WriteLine("31 days");

                break;

            case 11:

                Console.WriteLine("30 days");

                break;

            case 12:

                Console.WriteLine("31 days");

                break;

            default: 

                Console.WriteLine("invalid input");

                break;

        }

    }

}