object Main {

  def main(args: Array[String]): Unit = {
    val sc = new java.util.Scanner(System.in)

    val line = sc.nextLine()
    if (line.length < 8) {
      println("YES")
    } else if (line.count(_ == 'o') >= 8) {
      println("YES")
    } else println("NO")
  }

}