#include <iostream>
#include <cstdio>
#include <string>

using namespace std;

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

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

	if (pa == pb) {
		cout << -1 << endl;
	} else {
		bool win_a;
		if (pa.size() < pb.size()) {
			win_a = false;
		} else if (pa.size() > pb.size()) {
			win_a = true;
		} else {
			win_a = pa > pb;
		}
		cout << (win_a ? sa : sb) << endl;
	}
	return 0;
}