#include <iostream>
#include <algorithm>
using namespace std;
using ll = long long;

int main(){
	string s[3],t[3];
	cin >> s[0] >> s[1] >> s[2];
	cin >> t[0] >> t[1] >> t[2];
	if(s[1]>t[1])cout << s[0] << endl;
	else if(s[1]<t[1])cout << t[0] << endl;
	else cout << -1 << endl;
}