#include <bits/stdc++.h>
using namespace std;

int main()
{
	string Sa, Pa, Xa, Sb, Pb, Xb;
	cin >> Sa >> Pa >> Xa >> Sb >> Pb >> Xb;

	string ans;
	if( Pa.size() > Pb.size() ) ans = Sa;
	else if( Pa.size() < Pb.size() ) ans = Sb;
	else {
		for( int i = 0; i < Pa.size(); i++ ) {
			if( Pa[i] > Pb[i] ) {
				ans = Sa;
				break;
			}
			else if( Pa[i] < Pb[i] ) {
				ans = Sb;
				break;
			}
		}
	}
	if( ans.size() == 0 ) ans = "-1";

	cout << ans << endl;
}