Problem J

USING: io kernel math math.parser strings sequences locals ;

IN: template

:: test ( rtn cur -- a b )

  cur "" =
  [ rtn cur ]
  [
    cur 1 tail
    cur 1 head

    "(" =
    [ "(" rtn append  ]
    [
      rtn 1 head
      "(" =
      [ rtn 1 tail ]
      [ "X" rtn append ]
      if
    ]
    if

    swap
    test

  ]
  if ;


"Z"
readln
test

drop

"Z" =
[ "YES" ]
[ "NO" ]
if

print