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