Imports System

Module Program
	Public Function CountChar(ByVal s As String, ByVal c As Char)
		Return s.Length - s.Replace(c.ToString(), "").Length
	End Function
	Sub Main()
		Dim msg As String
		Dim S As String
		S = Console.ReadLine()
		Dim cnt As Integer
		Dim len As Integer = S.Length
		cnt = CountChar(S, "o")
		Dim nokori As Integer = 15 - len
		cnt = cnt + nokori

		If cnt >= 8 Then
			msg = "YES"
		Else
			msg = "NO"
		End If

		Console.WriteLine(msg)
	End Sub
End Module
