题解 | #杨辉三角的变形#

#include <iostream>
using namespace std;

int main() {
    int n;
    cin>>n;

    if (n==1||n==2){
        cout<<-1<<endl;
    }
    else{
        int a=(n-2)%4;
        switch (a){
            case 1: cout<<2<<endl;break;
            case 2: cout<<3<<endl;break;
            case 3: cout<<2<<endl;break;
            case 0: cout<<4<<endl;break;
        }
    }
    
    return 0;
}