import java.util.Scanner

object Main {
  val sc = new Scanner(System.in)
  def main(args: Array[String]): Unit = {
    val s = sc.next

    val k = s.length

    val res = if( (15 - k) + s.count(_ == 'o') >= 8) "YES" else "NO"

    println(res)

  }
}
