#include <iostream>

using namespace std;

int main() {
	int n;
	long long x, a, b;

	cin >> n >> x >> a >> b;

	int y = (1 << (n - 1));

	// cout << y << ", " << y - x << ", " << y - x + b - 1 << endl;

	int ans = min(
		(x + a - 1) / a,
		(y - x + b - 1) / b
	);

	cout << ans << endl;
	return 0;
}