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

int64_t divceil(int64_t a, int64_t b) {
	return a / b + (a % b ? 1 : 0);
}

int main() {
	int64_t N, X, A, B;
	cin >> N >> X >> A >> B;
	int64_t a = divceil(X, A), b = divceil( (1 << (N - 1)) - X, B);
	cout << min(a, b) << endl;
	return 0;
}