import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		while(sc.hasNext()){
			String sa=sc.next();
			String pa=sc.next();
			String xa=sc.next();
			String sb=sc.next();
			String pb=sc.next();
			String xb=sc.next();
			if(pa.equals(pb)) System.out.println(-1);
			else{
				if(pa.length()<pb.length()) System.out.println(sb);
				else if(pa.length()>pb.length()) System.out.println(sa);
				else{
					for(int i=0;i<pa.length();i++){
						if(pa.charAt(i)-'0'<pb.charAt(i)-'0'){
							System.out.println(sb);
							break;
						}
						else if(pa.charAt(i)-'0'>pb.charAt(i)-'0'){
							System.out.println(sa);
							break;
						}
					}
				}
			}
		}
	}
}