#include <stdio.h>

int DaysInMonth(int year, int month) {
	static int days[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
	
	if(month < 1 || month > 12) month = 1;
	if(month == 2) {
		return days[1] + 
			(year % 4 == 0 && year % 100 != 0 || year % 400 == 0);
	} else {
		return days[month - 1];
	}
}

int main(void) {
	int year;
	int month;
	int days;
	
	year = 2000;
	month = 2;
	
	days = DaysInMonth(year, month);
	printf("%d 年 %d 月は %d 日あります。\n", year, month, days);
	
	return 0;
}