题解 | #杨辉三角的变形#

#include <iostream>
using namespace std;

int main() {
    int n;
    while (cin >> n) {
        int index = -1;
        if(n>2){
            if(n%2==1) index = 2;
            else if(n%4==0) index = 3;
            else if(n%4==2) index = 4;
        }
        cout<<index<<endl; 
    }
}