object Main {
  def main(args: Array[String]) = {
    val sc = new java.util.Scanner(System.in)
    val S = sc.next
    sc.close()

    val remain = 15 - S.length
    val win = S.count(_ == 'o')

    remain + win match {
      case c if c >= 8 => println("YES")
      case _           => println("NO")
    }
  }
}