#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int needS = ceil(1.0 * a / v);
  int ans = 0;
  while (needS > 0) {
    ans++;
    int curS = 1;
    while (curS < k && b > 0) {
      curS++;
      b--;
    }
    needS -= curS;
  }
  cout << ans << endl;
  return 0;
}
