#include <bits/stdc++.h>
using namespace std;
struct debug_t {
  template <typename T>
  debug_t& operator<<(const T& value) {
    return *this;
  }
} debug;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int x = 1, result = 0;
  while (b-- && a > 0) {
    a -= v;
    if (++x == k) {
      x = 1;
      a -= v;
      result++;
    }
  }
  debug << "res = " << result << '\n';
  if (x != 1) {
    a -= v;
    result++;
  }
  debug << "res = " << result << '\n';
  debug << "a = " << a << '\n';
  if (a > 0) result += a / v + bool(a % v);
  cout << result;
}
