//計算某年某月有多少天

public class DayCounter 
{
    public static void main(String[ ] args) 
    {
        int yearIn = 2001;
        int monthIn = 2;
        if (args.length > 0)
            monthIn = Integer.parseInt(args[0]);
        if (args.length > 1)
            yearIn = Integer.parseInt(args[1]);
        System.out.println(monthIn + "/" + yearIn + " has "
            + countDays(monthIn, yearIn) + " days.");
    }

    static int countDays(int month, int year) 
    {
        int count = -1;
        switch (month) 
        {
            case 1:
            case 3:
            case 5:
            case 7:
            case 8:
            case 10:
            case 12:
                count = 31;
                break;
            case 4:
            case 6:
            case 9:
            case 11:
                count = 30;
                break;
            case 2:
                if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
                    count = 29;
                else
                    count = 28;
        }
        return count;
    }
}