package net.ipipip0129.yukicoder.no201;

import java.util.Scanner;

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

        String[] data = scan.nextLine().split(" ");
        String p1_name = data[0];
        String p1_point = data[1];

        data = scan.nextLine().split(" ");
        String p2_name = data[0];
        String p2_point = data[1];

        scan.close();

        int result = -1;

        if (p1_point.length() == p2_point.length()) {
            for (int i = 0; i < p1_point.length(); i++) {
                if (Integer.parseInt(String.valueOf(p1_point.charAt(i))) < Integer.parseInt(String.valueOf(p2_point.charAt(i)))) {
                    result = 1;
                    break;
                } else if (Integer.parseInt(String.valueOf(p1_point.charAt(i))) > Integer.parseInt(String.valueOf(p2_point.charAt(i)))) {
                    result = 0;
                    break;
                }
            }
        } else if(p1_point.length() < p2_point.length()) {
            result = 1;
        } else {
            result = 0;
        }

        switch (result) {
            case -1:
                System.out.println(-1);
                break;
            case 0:
                System.out.println(p1_name);
                break;
            case 1:
                System.out.println(p2_name);
                break;
        }
    }
}