#include <bits/stdc++.h> 

using namespace std;
typedef long long ll;

int main() {
    string sa, pa, xa, sb, pb, xb;
    cin >> sa >> pa >> xa;
    cin >> sb >> pb >> xb;

    if (pa.length() < pb.length()) {
        cout << sb << endl;
    } else if (pa.length() > pb.length()) {
        cout << sb << endl;
    } else {
        if (pa == pb) {
            cout << -1 << endl;
        } else if (pa < pb) {
            cout << sb << endl;
        } else {
            cout << sa << endl;
        }
    }
}