import java.util.Scanner

object Main {
  def main(args: Array[String]): Unit = {
    val sc = new Scanner(System.in)
    val writer = new java.io.PrintWriter(System.out)
    writer.println(solve(sc))
    writer.flush()
  }

  def solve(sc: Scanner): String = {
    val s = sc.next()
    val k = s.length
    val winCount = s.count(_ == 'o')
    debug(s, k, winCount)

    if (winCount + (15 - k) >= 8) "YES" else "NO"
  }

  private def debug(x: Any): Unit = {
    if (System.getenv("LOCAL_DEBUG") != null) println(x)
  }
}
