#include <iostream>
using namespace std;

int main(){
  string sa,sb,pa,pb,xa,xb;

  cin >> sa >> pa >> xa
      >> sb >> pb >> xb;
 
  if(pa.size()>pb.size())cout << sa;
  else if(pa.size()<pb.size())cout << sb;
  else if(pa==pb)cout << -1;
  else cout << (pa>pb?sa:sb);

  cout << endl;
  return 0;
}