#include <bits/stdc++.h>
int main() {
  int k, num, d, cap;
  scanf("%d %d %d %d", &k, &num, &d, &cap);
  int ans = 0;
  while (num > 0) {
    if (d) {
      if (d >= k - 1) {
        d -= k - 1;
        num -= k * cap;
        ans++;
        continue;
      } else {
        num -= (d + 1) * cap;
        d = 0;
        ans++;
        continue;
      }
    }
    num -= cap;
    ans++;
  }
  printf("%d\n", ans);
  return 0;
}
