#include <bits/stdc++.h>
using namespace std;
int min2(int x, int y) {
  if (x <= y)
    return x;
  else
    return y;
}
int main() {
  int k, a, b, v, res = 0;
  cin >> k >> a >> b >> v;
  int result = 0;
  for (int r = 1000; r >= 1; r--) {
    int temp = r + min2((k - 1) * r, b);
    if (temp * v >= a) result = r;
  }
  cout << result << endl;
  fclose(stdin);
  fclose(stdout);
  return 0;
}
