#include<iostream>
#include<cmath>
#include<string>

using namespace std;

int main(){

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

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

	if(PA==PB) cout<<"-1"<<endl;
	else if(PA>PB) cout<<SA<<endl;
	else cout<<SB<<endl;
}