#include<iostream>
#include<string>
#include<string.h>
#include<algorithm>
#include<stdio.h>
#include<cmath>
#include<vector>
#include<utility>
#include<stack>
#include<queue>
#include<list>
#include<bitset>
#include<functional>

#define FOR(i, a, b) for(int i=(a);i<=(b);i++)
#define RFOR(i, a, b) for(int i=(a);i>=(b);i--)
#define MOD 1000000007
#define INF 1000000000
#define PI 3.14159265358979

using namespace std;
typedef pair<int, int> P;

int main(void) {
	string sa, sb, xa, xb;
	string pa, pb;

	cin >> sa >> pa >> xa >> sb >> pb >> xb;
	if (pa.size() > pb.size()) {
		cout << sa << endl;
	}else if (pb.size() > pa.size()) {
		cout << sb << endl;
	}else if (pa > pb) {
		cout << sa << endl;
	}
	else if (pa < pb) {
		cout << sb << endl;
	}
	else {
		cout << -1 << endl;
	}

	return 0;
}