#include <iostream>
using namespace std;
int main(){
    string a,b,c,d,e;cin>>a>>b>>e>>c>>d>>e;
    
    if(b.size() == d.size()){
        for(int i = 0; b.size() > i; i++){
            if(b[i] > d[i]){
                cout << a << endl;
                return 0;
            }else if(b[i] < d[i]){
                cout << c << endl;
                return 0;
            }
        }
        cout << -1 << endl;
    }else{
        cout << (b.size()>d.size()?a:c) << endl;
    }
}