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