#include <bits/stdc++.h>
using namespace std;
int f(int k, int a, int b, int v) {
  if (a <= 0) return 0;
  if (b == 0) return (a % v == 0) ? a / v : (a / v) + 1;
  if (k - 1 <= b) return 1 + f(k, a - (k * v), b - k + 1, v);
  return 1 + f(k, a - (b + 1) * v, 0, v);
}
int main() {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  cout << f(k, a, b, v);
  return 0;
}
