C :

#include <stdio.h>
void main()
{
	int year,month,day;
	scanf("%d%d",&year,&month);
	switch(month)
	{
		case 1:case 3:case 5:case 7:case 8:	case 10:case 12:
			day=31;break;
		case 4:case 6:case 9:case 11:
			day=30;break;
		case 2:
			if(year%4==0&&year%100!=0||year%400==0)
				day=29;
			else
				day=28;	
	}
	printf("%d\n",day);	
}