import java.util.*;

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