666,NaCl也不NaCl了

#include <iostream>
using namespace std;
int main(){
    int year,month;
    cin >> year >> month;
    if(month == 2)
        if(year % 4 == 0 || year % 400 == 0)cout << 29;
        else cout << 28;
    if(month == 1 || month == 3 ||month == 5 ||month == 7 ||month == 8 ||month == 10 ||month == 12 )cout << 31;
    else if(month == 4 || month == 6 ||month == 9 ||month == 11)cout << 30;
    else cout << '输入不合法';
    return 0;
}