#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <string>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <stdio.h>
using namespace std;
#define int long long
int MOD = 1000000007;
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, X, A, B;
	cin >> N;
	cin >> X;
	cin >> A;
	cin >> B;
	int res = (X + A - 1) / A;
	cerr << res << endl;
	cerr << (((int)1 << (N - 1)) - X + B - 1) / B << endl;
	res = min(res, (((int)1 << (N - 1)) - X + B - 1) / B);
	cout << res << endl;
}