#include <iostream>
using namespace std;
int main(){
	long long N;
	cin >> N;
	long long X;
	cin >> X;
	long long A;
	cin >> A;
	long long B;
	cin >> B;
	cout << min((X + A - 1) / A, (((long long)
	1 << N - 1) - X + B - 1) / B) << endl;
}