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