样例2应该是对的，为什么WA了

#include<bits/stdc++.h>
using namespace std;

int main(){
	int y, m, a;
	cin >> y >> m;
	for(int i = 1000; i < 10000; i += 4){
		if(i == y) a == 1;
		else a == 0;
		if(i > y) break;
	}
	if(a == 1){
		if(m == 2) cout << 29;
		else{
			if(m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12) cout << 31;
			else cout << 30;
		}
	}else{
		if(m == 1 || m == 3 || m == 5 || m == 7 || m == 8 || m == 10 || m == 12) cout << 31;
		else if(m == 2) cout << 28;
		else cout << 30;
	}
	return 0;
}