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