#include<iostream>
#include<string>

int main() {
	std::string player1, player2;
	std::string player1_point, player2_point;
	char player1_te, player2_te;

	std::cin >> player1 >> player1_point >> player1_te;
	std::cin >> player2 >> player2_point >> player2_te;

	if (player1_point == player2_point) std::cout << -1 << std::endl;
	else if (player1_point > player2_point) std::cout << player1 << std::endl;
	else std::cout << player2 << std::endl;

	return 0;
}