#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int mod = 1e9 + 7;
const long long int INF = 1LL << 62;
long long int power(long long int x, long long int y) {
  long long int t = 1;
  while (y > 0) {
    if (y % 2)
      y -= 1, t = t * x % mod;
    else
      y /= 2, x = x * x % mod;
  }
  return t;
}
long long int inverse(long long int q) {
  long long int t;
  t = power(q, mod - 2);
  return t;
}
long long int gcd(long long int a, long long int b) {
  long long int c;
  if (b == 0)
    return a;
  else
    while (b != 0) {
      c = b;
      b = a % b;
      a = c;
    }
  return a;
}
int main() {
  long long int k, a, b, v, i, j, l, g, h;
  cin >> k >> a >> b >> v;
  l = 0;
  while (a > 0) {
    g = k - 1;
    if (b >= g) {
      b -= g;
      h = g;
    } else {
      h = b;
      b = 0;
    }
    if (h < 0) {
      h = 0;
    }
    a -= ((h + 1) * v);
    l++;
  }
  cout << l << endl;
  return 0;
}
