80分求改！

#include<stdio.h>
int main ()
{
	int year,month;
	scanf("%d%d",&year,&month);
	int a;
	if(year%4==0&&year%100!=0)
		a=1;
	else if(year%400==0)
		a=1;
	else
		a=0;
		
	if(a=1&&month==2)
		printf("29");
	else if(a=0&&month==2)
		printf("28");
	else if(month==1||month==3||month==5||month==7||month==8||month==10||month==12)
		printf("31");
	else 
		printf("30");
	return 0;
}