#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int ots;
  if (a % v == 0)
    ots = a / v;
  else
    ots = a / v + 1;
  int ans = 0;
  while (1) {
    if (ots <= 0) break;
    ans++;
    int x = min(b + 1, k);
    ots = ots - x;
    b = b - x + 1;
  }
  cout << ans;
  return 0;
}
