题解

#include<iostream>
using namespace std;
int main(){
    int month;
	cin>>month;
    if(month==1||month==3||month==5||month==7||month==8||month==10||month==12){
		cout<<31;
    }if(month==2){
		cout<<28;
    }else if(month==4||month==6||month==9||month==11){
        cout<<30;
    }
	return 0;
}