#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1000000007;
int f(int x) {
  if (x < 10) return 0;
  int sum = 0;
  for (; x > 0; x /= 10) sum += x % 10;
  return 1 + f(sum);
}
int main(int argc, char* argv[]) {
  int k, a, b, v;
  cin >> k >> a >> b >> v;
  int n = a / v;
  if (n * v != a) n++;
  int answer = 0;
  while (b >= k && n > 0) {
    b -= k - 1;
    n -= k;
    answer++;
  }
  if (n > 0) {
    n -= b + 1;
    answer++;
    if (n > 0) answer += n;
  }
  cout << answer << endl;
  return 0;
}
