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