import java.util.Scanner;


public class Main_yukicoder201 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String[] s = new String[2];
        String[] p = new String[2];
        String[] x = new String[2];
        for (int i = 0; i < 2; i++) {
        	s[i] = sc.next();
        	p[i] = sc.next();
        	x[i] = sc.next();
        }

        int res = p[0].compareTo(p[1]);
        if (p[0].length() > p[1].length()) {
        	System.out.println(s[0]);
        } else if (p[0].length() < p[1].length()) {
        	System.out.println(s[1]);
        } else {
        	if (res > 0) {
        		System.out.println(s[0]);
        	} else if (res < 0) {
        		System.out.println(s[1]);
        	} else {
        		System.out.println("-1");
        	}
        }
        
        sc.close();
    }
}