#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, k, v, s = 0;
  scanf("%lld%lld%lld%lld", &k, &a, &b, &v);
  while (1) {
    long long x = 0;
    for (;;) {
      b--;
      a -= v;
      x++;
      if (b < 0 || x >= k) {
        b++;
        break;
      }
    }
    s++;
    if (a <= 0) break;
  }
  printf("%lld", s);
  return 0;
}
