#include <iostream>
#include <random>
using namespace std;

int main(){
	string SA, PA, SB, PB, dummy;
	cin >> SA >> PA >> dummy >> SB >> PB >> dummy;
	if(PA.size() > PB.size()){
		cout << SA << endl;
	}else if(PA.size() < PB.size()){
		cout << SB << endl;
	}else if(PA > PB){
		cout << SA << endl;;
	}else if(PA < PB){
		cout << SB << endl;
	}else{
		cout << -1 << endl;
	}
}