#include <algorithm>
#include <iostream>
#include <iomanip>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
#include <cmath>
using namespace std;

#define FOR(i,s,e) for (int i = int(s); i != int(e); i++)
#define FORIT(i,c) for (typeof((c).begin()) i = (c).begin(); i != (c).end(); i++)
#define ISEQ(c) (c).begin(), (c).end()



int main(){
	string SA,PA,RA;
	string SB,PB,RB;
	cin >> SA >>  PA >>RA;
	cin >> SB  >>  PB  >>RB;

	string w;
	if(PA.length()<PB.length()){
		w = SB;
	}else if(PA.length()>PB.length()){
		w = SA;
	}else{
		if (PA == PB) w = "-1";
		else if(PA < PB) w = SB;
		else w = SA;
	}

	cout << w << endl;
	return 0;
}