思路

What can I say?

code

#include<bits/stdc++.h>
using namespace std;
int y,m;
bool check(int n){
	return n%400==0||(n%4==0&&n%100!=0);
}
int main(){
	cin>>y>>m;
	if(m==1||m==3||m==5||m==7||m==8||m==10||m==12)	cout<<31;
	else if(m==4||m==6||m==9||m==11)	cout<<30;
	else cout<<28+check(y);
}