#include <bits/stdc++.h>
using namespace std;
const int MAXN = 4e5 + 5;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
const long long INF = 0x3f3f3f3f3f3f3f3f;
int main() {
  int k, a, b, v;
  scanf("%d%d%d%d", &k, &a, &b, &v);
  int ans = 0;
  while (a > 0) {
    if (b >= k - 1) {
      b = b - (k - 1);
      a = a - k * v;
    } else {
      a = a - (b + 1) * v;
      b = 0;
    }
    ans++;
  }
  printf("%d\n", ans);
  return 0;
}
