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