object Dups {
  def duplicateCount(str: String): Int ={
    def helper (str:String, acc:Int): Int ={
      if(str.length>1) {
        val str1 = str.toLowerCase.filterNot(str.toLowerCase.charAt(0).toString.toSet)
        if(str.length-str1.length>1){
          helper(str1,acc+1)
        }
        else helper(str1,acc)
      }
      else acc
    }
    helper(str,0)
  }
}