var arr=readLine()!.characters.split{$0==" "}.map{(String($0))}

var win : Int = 0
for character in arr[0].characters {
	if( character == "o" ) {
      win += 1
    }
}

( ( 15 - arr[0].characters.count + win ) >= 8 ) ? print( "YES" ) : print( "NO" ) 