#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <cctype>
#include <cmath>
#include <iostream>
#include <queue>
#include <list>
#include <map>
#include <numeric>
#include <set>
#include <sstream>
#include <string>
#include <vector>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;

int calc(const string& a, const string& b){
  if(a==b) return 0;
  if(a.size() < b.size()) return -1;
  if(a.size() > b.size()) return 1;
  
  rep(i,a.size()){
    if(a[i]-'0' < b[i]-'0') return -1;
    if(a[i]-'0' > b[i]-'0') return 1;
  }
  return 0;
}

int main(){
  string a,b,c,d,e,f;
  cin >> a >> b >> c;
  cin >> d >> e >> f;

  int res = calc(b,e);
  if(res == 1){
    cout << a << endl;
  }
  if(res == 0){
    cout << -1 << endl;
  }
  if(res == -1){
    cout << d << endl;
  }
  
  return 0;
}