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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    ll N, X, A, B, ans;
    cin >> N >> X >> A >> B;
    ans = (X + A - 1) / A;
    ans = min(ans, ((1ll << (N - 1)) - X + B - 1) / B);
    cout << ans << '\n';
}