#include <bits/stdc++.h>
using namespace std;
int main() {
  long long K, A, B, V;
  cin >> K >> A >> B >> V;
  long long nuts = A;
  long long divisors = B;
  long long capacity = V;
  long long maxSections = K;
  int boxes = 0;
  while (nuts > 0) {
    boxes++;
    int sections = min(divisors + 1, maxSections);
    nuts -= sections * capacity;
    divisors -= sections - 1;
  }
  cout << boxes;
  return 0;
}
