#include <bits/stdc++.h>
using namespace std;
int main() {
  int max_sec, nuts, divisor, capacity, cont = 0, box = 0, sec = 1;
  cin >> max_sec >> nuts >> divisor >> capacity;
  while (nuts != 0) {
    if (box == 0) cont++;
    if (nuts >= capacity) {
      box += capacity;
      nuts -= capacity;
    } else {
      box += capacity;
      nuts -= nuts;
    }
    if (max_sec > sec && divisor != 0) {
      sec++;
      divisor--;
    } else if (max_sec == sec || divisor == 0) {
      box = 0;
      sec = 1;
    }
  }
  cout << cont << endl;
  return 0;
}
