#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a, b, v, count = 0;
  scanf("%d %d %d %d", &k, &a, &b, &v);
  while (a > v) {
    if (k - 1 <= b) {
      a = a - k * v;
      b = b - (k - 1);
      count++;
    } else {
      a = a - (b + 1) * v;
      count++;
      b = 0;
    }
  }
  if (a > 0)
    printf("%d\n", count + 1);
  else
    printf("%d\n", count);
  return 0;
}
