#include<bits/stdc++.h>
using namespace std;

int main(){
    string sa,pa,xa,sb,pb,xb; cin >> sa >> pa >> xa >> sb >> pb >> xb;
    if(pa.size() > pb.size()){
        cout << sa << endl;
    }else if(pa.size() < pb.size()){
        cout << sb << endl;
    }else if(pa > pb){
        cout << sa << endl;
    }else if(pa < pb){
        cout << sb << endl;
    }else{
        cout << -1 << endl;
    }
}