package m.shin;
import java.util.Scanner;
public class Con201 {

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

		if(pa.length() > pb.length()){
			System.out.println(sa);
		}else if(pa.length() < pb.length()){
			System.out.println(sb);
		}else{
			for(int i = 0;i < pa.length();i++){
				int a = Integer.parseInt(pa.substring(i , i+1));
				int b = Integer.parseInt(pb.substring(i , i+1));
				if(a > b){
					System.out.println(sa);
					break;
				}else if(a < b){
					System.out.println(sb);
					break;
				}
				if(i == pa.length() -1){
					System.out.println(-1);
				}
			}
		}

	}

}