#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v, s1 = 0, s2 = 0;
  cin >> k >> a >> b >> v;
  while (a > 0) {
    s1++;
    a = a - v;
  }
  while (s1 > 0) {
    if (k - 1 <= b) {
      b = b - (k - 1);
      s1 = s1 - k;
      s2++;
    } else {
      if (b > 0) {
        s1 = s1 - (b + 1);
        b = 0;
        s2++;
      } else {
        s2 = s2 + s1;
        s1 = 0;
      }
    }
  }
  cout << s2 << endl;
}
