#define _GLIBCXX_DEBUG
#define ll long long
#define INF 1000000000;
#define INF_B 1000000000000000000;
#include <bits/stdc++.h>
using namespace std;
using Graph = vector<vector<int>>;

int main(){
  string S1, P1, D, S2, P2; cin >> S1 >> P1 >> D >> S2 >> P2 >> D;
  int p1 = (int)P1.size(), p2 = (int)P2.size();
  if(p1 == p2){
    for(int i = 0; i < p1; i++){
      if(P1[i] < P2[i]){
        cout << S2 << endl;
        return 0;
      }else if(P1[i] > P2[i]){
        cout << S1 << endl;
        return 0;
      }
    }
    cout << -1 << endl;
  }else{
    if(p1 < p2) cout << S2 << endl;
    else cout << S1 << endl;
  }
}