import java.util.Scanner;

class Main{
	public static void main(String[] args) {
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong(),x=sc.nextLong(),a=sc.nextLong(),b=sc.nextLong();
		sc.close();
		if((x+a-1)/a>((long)Math.pow(2, n-1)-1-x+b)/b) System.out.print(((long)Math.pow(2, n-1)-1-x+b)/b);
		else System.out.print((x+a-1)/a);
	}
}