#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int k, a, b, v;
  scanf("%d %d %d %d", &k, &a, &b, &v);
  int need = a / v;
  if (a % v != 0) need++;
  int total = 0;
  while (true) {
    if (need <= 0) break;
    if (b >= (k - 1)) {
      need -= k;
      total++;
      b -= k - 1;
    } else if (b > 0) {
      need -= b + 1;
      total++;
      b = 0;
    } else {
      total++;
      need--;
    }
  }
  printf("%d", total);
  return 0;
}
