#include <iostream>
#include <string>

using namespace std;

int main() {

    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

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

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