#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <map>
#include <stack>
#include <cmath>
#include <queue>
#include <numeric>


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

	std::cin >> n >> x >> a >> b;

	long long kaihuku = std::ceil(((1 << (n - 1)) - x) / (double)b);
	long long attack = std::ceil(x / (double)a);


	std::cout << std::min(kaihuku, attack) << std::endl;

	return 0;
}