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