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