import scala.annotation.tailrec
import scala.collection.mutable

object Main extends App {

  import scala.io.StdIn._
  import scala.math._
  val n = readLine.trim.toInt
  val answers = readLine.trim.toList.map{_ == 'o'}
  println(
    count(answers)
  )
  @tailrec
  def count(answers: List[Boolean], result: Int = 0): Int = {
    answers match {
      case Nil ⇒ result
      case false::false::t ⇒ result + 1
      case _::t ⇒ count(t, result + 1)
    }
  }
  implicit class Extension[T](val value :T){
    def also(func: T ⇒ Unit): T = {
      func(value)
      value
    }
    def let[R](func: T ⇒ R): R = func(value)
  }
}
