#include<bits/stdc++.h>
using namespace std;
int main(){
  string p1,p2,s1,s2,g;
  cin>>p1>>s1>>g>>p2>>s2>>g;
  int l1=s1.length();
  int l2=s2.length();
  if(l1>l2){
    cout<<p1<<endl;
    return 0;}
  if(l2>l1){
    cout<<p2<<endl;
    return 0;}
  for(int i=0;i<l1;i++){
    if(s1[i]>s2[i]){
      cout<<p1<<endl;
      return 0;}
    if(s2[i]>s1[i]){
      cout<<p2<<endl;
      return 0;}
  }
  cout<<-1<<endl;
}