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

int main() {
  string sa, pa, xa, sb, pb, xb;
  cin >> sa >> pa >> xa >> sb >> pb >> xb;
  if (pa.length() > pb.length()) cout << sa << endl;
  else if (pa.length() < pb.length()) cout << sb << endl;
  else if (pa > pb) cout << sa << endl;
  else if (pa < pb) cout << sb << endl;
  else cout << -1 << endl;
}