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

int main() {
    string a, b, c, d, e, f;
    cin>>a>>b>>c>>d>>e>>f;
    if (b.size() > e.size()) cout << a << endl;
    else if (b.size() < e.size()) cout << d << endl;
    else if (b==e) puts("-1");
    else if (b > e) cout << a << endl;
    else cout << d << endl;
    return 0;
}