let s = read_line () in
let string_count f s =
  let count = ref 0 in
  String.iter (fun c -> if f c then incr count) s;
  !count in
let n = string_count (fun c -> c = 'o') s in
let rest = 15 - String.length s in
print_endline @@ if n + rest >= 8 then "YES" else "NO"