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