import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int s = sc.nextInt() - 1;
		int t = sc.nextInt() - 1;
		int k = sc.nextInt();
		int[] a = new int[n];
		for (int i = 0; i < n; i++) {
			a[i] = sc.nextInt();
		}
		sc.close();

		int min = 1000000007;
		for (int i = 0; i < n; i++) {
			if (i != s && i != t) {
				min = Math.min(min, a[i]);
			}
		}
		if (a[s] + a[t] <= k) {
			System.out.println(1);
		} else if (a[s] + min <= k && a[t] + min <= k) {
			System.out.println(2);
		} else {
			System.out.println(-1);
		}
	}
}