#include <bits/stdc++.h>
using namespace std;
const int MAX = numeric_limits<int>::max();
const int MIN = -MAX - 1;
int main() {
  int maxSections, nuts, divisors, nutsPerSection;
  cin >> maxSections >> nuts >> divisors >> nutsPerSection;
  int box = 0;
  while (nuts > 0) {
    if (divisors) {
      int use = min(divisors + 1, maxSections);
      divisors -= (use - 1);
      use *= nutsPerSection;
      nuts = max(0, nuts - use);
    } else {
      nuts -= nutsPerSection;
    }
    box++;
  }
  cout << box;
}
