#include <iostream>
#include <cmath>
using namespace std;
int main(void){
    long long a,b,c = -1;
    cin >> a >> b;
    for(long long i=2;i<=(a+b)/2;i++){
        cout << a << " " << b << endl;
        if( (a+b)%i==0 ){
            c = i;
            break;
        }
    }
    cout << c;
    
}