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