啊哈哈哈哈~题解来咯~

#include<bits/stdc++.h>
using namespace std;
 int main()
 {
 	int n;
    int yt[13] = {0,31,28,31,30,31,30,31,31,30,31,30,31};
    cin>>n;
    int c = 0;
    for(int i=1;i<=12;i++){
        if((12+c+n) %7  == 5) cout<<i<<endl;
        c+=yt[i];
    }
 	         
 	return 0;
 }