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