#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int,int>;
#define rep(i,n) for(int i=0;i<n;i++)

const ll mod = ll(1e9) + 7;
const int INF = 1<<29;

int main(){
    string sa,sb,pa,pb,xa,xb;
    cin >> sa >> pa >> xa >> sb >> pb >> xb;
    string ans;
    if (pa.size()>pb.size()) ans = sa;
    else if (pa.size()<pb.size()) ans = sb;
    else{
        rep(i,pa.size()){
            if (pa[i]>pb[i]){
                ans = sa;
                break;
            }
            else if (pa[i]<pb[i]){
                ans = sb;
                break;
            }
            else if (i==pa.size()-1) ans = "-1";
        }
    }
    cout << ans << endl;
    return 0;
}