#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, n)           for(int(i)=0;(i)<(n);++(i))
#define FOR(i, f, t)        for(int(i)=(f);(i)<(t);(++i))
const int MOD = int(1e9+9);

int main(){
    string sa, pa, xa;
    string sb, pb, xb;
    cin >> sa >> pa >> xa;
    cin >> sb >> pb >> xb;
    if(pa.size() > pb.size() || pa.size() == pb.size() && pa > pb){
        cout << sa << endl;
        return 0;
    }
    if(pa.size() < pb.size() || pa.size() == pb.size() && pa < pb){
        cout << sb << endl;
        return 0;
    }
    cout << -1 << endl;
    return 0;
}