import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String sa, sb, pa, pb, xa, xb;
        sa = in.next();
        pa = in.next();
        xa = in.next();
        sb = in.next();
        pb = in.next();
        xb = in.next();

        if(pa.length() > pb.length()) {
            System.out.println(sa);
        } else if(pb.length() > pa.length()) {
            System.out.println(sb);
        } else {
            int t = pa.compareTo(pb);
            if(t > 0) System.out.println(sa);
            else if(t < 0) System.out.println(sb);
            else System.out.println(-1);
        }
    }
}