import java.util.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		long x = sc.nextInt();
		long a = sc.nextInt();
		long b = sc.nextInt();
		long max = (long)(Math.pow(2, n - 1));
		long count = Math.min((x + a - 1) / a, (max - x + b - 1) / b);
		System.out.println(count);
	}
}