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