#include<bits/stdc++.h>
using namespace std;
using ll = long long;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    string name0; cin >> name0;
    string power0; cin >> power0;
    ll L0 = power0.size();
    char c; cin >> c;
    
    string name1; cin >> name1;
    string power1; cin >> power1;
    ll L1 = power1.size();
    cin >> c;

    if(L0>L1){
        p(name0);
    }else if(L0<L1){
        p(name1);
    }else{
        if(power0==power1){
            p(-1);
        }else{
            FOR(i, 0, L0){
                if(power0[i]==power1[i]) continue;
                if(power0[i]<power1[i]){
                    p(name1);
                }else{
                    p(name0);
                }
                return 0;
            }
        }
    }
    
    return 0;
}