看下呗

#include<iostream>
#include<cstdio>
using namespace std;
int main(){
    int year,month,day;
    scanf("%d",&year);
    scanf("%d",&month);
    if(month<8){
        if(month%2==1){
            day=30;
        }else{
            day=31;    
        }
    }else{
        if(month%2==0){
            day=30;
        }else{
            day=31;    
        }
    }
    if(month==2){
        if(year%4==0&&year%100!=0){
            day=29;
        }else if(year%400==0){
            day=29;
        }else{
            day=28;
        }
    }
    printf("%d ",day);
    return 0;
}