#define _USE_MATH_DEFINES

#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin
#include <ios>			//fixed
#include <iomanip>		//setprecision
#include <sstream>		//stringstream
#include <numeric>		//gcd, assumlate
#include <random>		//randam_device
#include <limits>		//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	string SA, PA, XA;
	string SB, PB, XB;
	cin >> SA >> PA >> XA >> SB >> PB >> XB;

	if (PA == PB) {
		cout << -1 << endl;
		return 0;
	}

	if (PA.length() > PB.length()) {
		cout << SA << endl;
	}
	else if (PA.length() < PB.length()) {
		cout << SB << endl;
	}
	else {
		for (unsigned int i = 0; i < PA.length(); i++) {
			if (PA[i] > PB[i]) {
				cout << SA << endl;
				return 0;
			}
			if (PA[i] < PB[i]) {
				cout << SB << endl;
				return 0;
			}
		}
	}

	return 0;

}