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