#include <iostream>
#include <string>
#include <stdlib.h>
using namespace std;


int main(void){
	string S_A,P_A,X_A,S_B,P_B,X_B,ans;
	string ss_a,ss_b;
	int i_a, i_b;

	cin >> S_A >> P_A >> X_A;
	cin >> S_B >> P_B >> X_B;
	if(P_A.length()>P_B.length()) {
		ans = S_A;
	} else if(P_A.length()<P_B.length()) {
		ans = S_B;
	} else if(P_A == P_B){
		ans = "-1";
	} else {
		for(int i=0;i<P_A.length();i++){
			ss_a = P_A.substr(i,1);
			ss_b = P_B.substr(i,1);
			i_a = atoi(ss_a.c_str());
			i_b = atoi(ss_b.c_str());
			if(i_a > i_b) {
				ans = S_A;
				break;
			} else if(i_a < i_b){
				ans = S_B;
				break;
			}
		}
	}
	cout << ans << endl;
	return 0;
}