#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int x = (a + v - 1) / v;
  int t, y;
  t = b / (k - 1);
  y = t * k;
  while (y > x) {
    b--;
    t = b / (k - 1);
    y = t * k;
  }
  int c;
  c = b % (k - 1) + 1;
  int m;
  if (x > c + y)
    m = x - (c + y);
  else
    m = 0;
  if (y < x)
    cout << m + t + 1;
  else
    cout << m + t;
  return 0;
}
