import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int N = scan.nextInt();
		int X = scan.nextInt();
		int A = scan.nextInt();
		int B = scan.nextInt();
		scan.close();
		long max = (long)Math.pow(2, N - 1);
		int t1 = (int)Math.ceil((double)X / A);
		int t2 = (int)Math.ceil(((double)max - X) / B);
		int ans = Math.min(t1, t2);
		System.out.println(ans);
	}
}