#include <bits/stdc++.h>
using namespace std;

int main() {
	int64_t n, x, a, b;
	cin >> n >> x >> a >> b;
	cout << min((x + a - 1) / a, (int64_t(pow(2, n - 1)) - x + b - 1) / b) << endl;
	return 0;
}