#include <bits/stdc++.h>
using namespace std;
int main() {
	string Sa, Sb, Pa, Pb;
	cin >> Sa >> Pa >> Sb >> Sb >> Pb;
	int ans = 0;
	if(Pa.length() == Pb.length()) {
		for(int i = 0; i < Pa.length(); i++) {
			if(Pa[i] > Pb[i]) {
				ans = 1; break;
			}
			if(Pa[i] < Pb[i]) {
				ans = -1; break;
			}
		}
	} else {
		ans = (Pa.length() > Pb.length() ? 1 : -1);
	}
	cout << (ans ? (ans > 0 ? Sa : Sb) : "-1") << endl;
	return 0;
}