#include<bits/stdc++.h>

using namespace std;

using int64 = long long;

int main()
{
  int64 N, X, A, B;
  cin >> N >> X >> A >> B;
  int64 sq = 1;
  for(int i = 0; i < N - 1; i++) sq *= 2;
  int64 sa = sq - X;
  cout << min((X + A - 1) / A, (sa + B - 1) / B) << endl;
}