#include <bits/stdc++.h>
int main() {
  int k, a, b, v, sectionsrequired, boxes, s;
  scanf("%d %d %d %d", &k, &a, &b, &v);
  sectionsrequired = a / v;
  if (a % v != 0) sectionsrequired++;
  s = sectionsrequired;
  if (s <= b + 1) {
    boxes = s / k;
    if (s % k != 0) boxes = s / k + 1;
  } else
    boxes = s - b;
  printf("%d", boxes);
  return 0;
}
