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