#include <bits/stdc++.h>
#define PI 3.14159265359
using namespace std;
const int64_t mod = 1e9 + 7;

int main() {
	string Sa, Sb, Pa, Pb, Xa, Xb;
	cin >> Sa >> Pa >> Xa;
	cin >> Sb >> Pb >> Xb;

	if (Pa.size() == Pb.size()) {
		if (Pa == Pa) {
			cout << -1 << endl;
		}
		else if (Pa > Pb) {
			cout << Sa << endl;
		}
		else {
			cout << Sb << endl;
		}
	}
	else if (Pa.size() > Pb.size()) {
		cout << Sa << endl;
	}
	else {
		cout << Sb << endl;
	}
}