#include<iostream>
#include<cassert>
using namespace std;
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int N;
	long X,A,B;
	cin>>N>>X>>A>>B;
	cout<<min((X+A-1)/A,((1L<<N-1)-X+B-1)/B)<<endl;
}