package me.yukicoder.lv1_5;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class No0201 {
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] inputA = br.readLine().split(" ");
		String[] inputB = br.readLine().split(" ");
		long a = Long.parseLong(inputA[1]);
		long b = Long.parseLong(inputB[1]);

		if (a > b) {
			System.out.println(inputA[0]);
		} else if (a < b) {
			System.out.println(inputB[0]);
		} else {
			System.out.println(-1);
		}
	}
}