#include<iostream>
#include<stdio.h>

using namespace std;

int main(){

    string sa, pa, xa, sb, pb, xb;
    cin>> sa>> pa>> xa;
    cin>> sb>> pb>> xb;

    if(pa.size() == pb.size()){
        if(pa < pb){
            cout<< sb<< endl;
        }else if(pa > pb){
            cout<< sa<< endl;
        }else{
            cout<< "-1"<< endl;
        }
    }else if(pa.size() < pb.size()){
        cout<< sb<< endl;
    }else{
        cout<< sa<< endl;
    }
    return 0;
}