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

int main() {
  string nA, nB, pA, pB, xA, xB;

  cin >> nA >> pA >> xA >> nB >> pB >> xB;
  
  if (pA.size()>pB.size()) {
    cout << nA << endl;
  } else if (pA.size()<pB.size()) {
    cout << nB << endl;
  } else {
    if (pA>pB) {
      cout << nA << endl;
    } else if (pA<pB) {
      cout << nB << endl;
    } else {
      cout << -1 << endl;
    }
  }
}