text: #!/usr/bin/env python3
  
  # https://codeforces.com/problemset/problem/402/A
  
  def f(l):
      k,a,b,v = l
      ns = (a+v-1)//v
      return max(ns-b,(ns+k-1)//k) 
  
  l = list(map(int,input().split()))
  print(f(l))
  