#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int main() {
  string sa,pa,xa,sb,pb,xb;
  cin >> sa >> pa >> xa >> sb >> pb >> xb;
  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;
  }
}