import qualified Data.IntMap.Strict as M
import Data.List
import Data.Bits

mapKeysValue f g = M.fromDistinctAscList . map (\(k,v) -> (f k, g v)) . M.toList

main = do
 n <- readLn
 let takeFellow = reverse . takeWhile (/=(-1)) . reverse
 fs <- concat . map (takeFellow . map read . words) . lines <$> getContents
 print (idolUnit n fs)

idolUnit n fs = (snd . M.findMax) (foldl dp (M.singleton 0 0) units)
 where units = zip [(bit i, bit j) | i<-[0..n-1], j<-[0..n-1], i<j] fs

dp im ((bi,bj),f) =  M.filterWithKey (\k _ -> mod k bi == mod (complement 0) bi) $ M.unionWith max im $ mapKeysValue (.|. ab) (+f) im'
 where
  ab = bi .|. bj
  im' = M.filterWithKey (\k _ -> k .&. ab == 0) im