#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 10;
const double pi = 3.1415926;
int k, a, b, v;
int ans = 0;
int main() {
  ios::sync_with_stdio(false);
  cin >> k >> a >> b >> v;
  while (a > 0) {
    int x;
    while (b > 0) {
      if (a <= 0) break;
      if (b >= k) {
        x = k - 1;
        b -= x;
        a -= k * v;
        ans++;
      } else {
        x = b;
        b -= x;
        a -= (x + 1) * v;
        ans++;
      }
    }
    if (a > 0) {
      a -= v;
      ans++;
    }
  }
  cout << ans << endl;
}
