Кирилл Деменев

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        int month;

        Scanner in = new Scanner(System.in);

        month = in.nextInt();

        switch(month) {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                System.out.println(31);
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                System.out.println(30);
                break;
            case 2:
                System.out.println(28);
                break;
        }
    }
}