#include <bits/stdc++.h>
using namespace std;
int main(void) {
  double a, v;
  int b, num_sec, k, result;
  int num_box;
  while (cin >> k >> a >> b >> v) {
    num_box = 0;
    num_sec = b + 1;
    result = ceil(a / v);
    if (num_sec > k) {
      while ((num_sec) > k && result > k) {
        result -= k;
        num_sec -= (k - 1);
        num_box++;
      }
      if (result <= num_sec)
        num_box += 1;
      else
        num_box = num_box + result - num_sec + 1;
      cout << num_box << endl;
    } else {
      if (result <= num_sec)
        cout << 1 << endl;
      else
        cout << result - num_sec + 1 << endl;
    }
  }
  return 0;
}
