#include <bits/stdc++.h>
#define REP(i, a, n) for(ll i = ((ll) a); i < ((ll) n); i++)
using namespace std;
typedef long long ll;

ll N, X, A, B;

int main(void) {
  cin >> N >> X >> A >> B;

  cout << min((X + A - 1) / A, ((1LL << (N - 1)) - X + B - 1) / B) << endl;
}