#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int boxes = 0;
  while (a > 0) {
    if (b >= k) {
      a -= (k * v);
      b -= (k - 1);
      boxes++;
      continue;
    }
    if (k > b - 1 && b != 0) {
      a -= ((b + 1) * v);
      b = 0;
      boxes++;
      continue;
    }
    a -= v;
    boxes++;
  }
  cout << boxes << endl;
  return 0;
}
