{-# LANGUAGE BangPatterns      #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TupleSections     #-}

import           Control.Monad
import           Control.Monad.Fix
import           Control.Monad.State
import           Data.Bits 
import           Data.Char
import           Data.Coerce
import qualified Data.Foldable                     as F
import           Data.IORef
import           Data.Word
import           Unsafe.Coerce
import qualified Data.ByteString.Char8             as BSC8
import qualified GHC.Integer.GMP.Internals         as GMP
import qualified Data.Vector.Fusion.Stream.Monadic as VFSM
import qualified Data.Vector.Unboxed               as VU
import qualified Data.Vector.Unboxed.Mutable       as VUM

main :: IO ()
main = do
  n  <- readLn :: IO Int
  xs <- radixSort <$> seqInput n
  ys <- VU.unsafeThaw xs
  ans <- newIORef (-1 :: Int)
  fix $ \loop -> do
    x <- newIORef (0 :: Int)
    rep n $ \i -> do
      item <- VUM.unsafeRead ys i
      if (item >= 10)
        then do
          modifyIORef' x (* 100)
          modifyIORef' x (+ item)
        else do
          modifyIORef' x (* 10)
          modifyIORef' x (+ item)
    item1 <- readIORef ans
    item2 <- readIORef x
    when (item1 < item2 && millerRabin item2) $ do
      when (item2 > item1) $ writeIORef ans item2
    b <- VUM.nextPermutation ys
    when b loop
  print =<< readIORef ans

millerRabin :: Int -> Bool
millerRabin k
  | k <= 3 = k == 2 || k == 3
  | even k = False
  | otherwise = mr k
  where
    mr :: Int -> Bool
    mr n
      | n < 2047            = loop [2]
      | n < 1373653         = loop [2,3]
      | n < 9080191         = loop [31,73]
      | n < 25326001        = loop [2,3,5]
      | n < 4759123141      = loop [2,7,61]
      | n < 1122004669633   = loop [2,13,23,1662803]
      | n < 2152302898747   = loop [2,3,5,7,11]
      | n < 3474749660383   = loop [2,3,5,7,11,13]
      | n < 341550071728321 = loop [2,3,5,7,11,13,17]
      | otherwise           = loop [2,325,9375,28178,450775,9780504,1795265022]
      where
        !m = n - 1
        !s = ctz m
        !d = m .>>. s
        loop :: [Int] -> Bool
        loop [] = True
        loop (a:as)
          | powModInt a d n /= 1 && allok = False
          | otherwise = loop as
          where allok = all (\r -> (powModInt a ((1 .<<. r) * d) n) /= m) $ [0..(s - 1)]

radixSort64 :: VU.Vector Word64 -> VU.Vector Word64
radixSort64 vword = F.foldl' step vword [0,16,32,48]
  where
    mask k x = fromIntegral $ x .>>. k .&. 0xffff
    step v k = VU.create $ do
      pref <- VU.unsafeThaw
            . VU.prescanl' (+) 0
            . VU.unsafeAccumulate (+) (VU.replicate 0x10000 0)
            $ VU.map ((, 1) . mask k) v
      res <- VUM.unsafeNew $ VU.length v
      VU.forM_ v $ \x -> do
        let !masked = mask k x
        i <- VUM.unsafeRead pref masked
        VUM.unsafeWrite pref masked $ i + 1
        VUM.unsafeWrite res i x
      return res
{-# INLINE radixSort64 #-}

radixSort :: (VU.Unbox a, Word64Encode a) => VU.Vector a -> VU.Vector a
radixSort = VU.map decode64 . radixSort64 . VU.map encode64
{-# INLINE radixSort #-}

radixSortInt :: VU.Vector Int -> VU.Vector Int
radixSortInt = unsafeCoerce . radixSort64 . unsafeCoerce

radixSortNonNegative :: (VU.Unbox a, Word64Encode a) => VU.Vector a -> VU.Vector a
radixSortNonNegative = VU.map decodeNonNegative64 . radixSort64 . VU.map encodeNonNegative64
{-# INLINE radixSortNonNegative #-}

radixSort32 :: VU.Vector Word32 -> VU.Vector Word32
radixSort32 vec = F.foldl' step vec [0, 16]
  where
    mask k x = fromIntegral $ x .>>. k .&. 0xffff
    step v k = VU.create $ do
      pref <- VU.unsafeThaw
            . VU.prescanl' (+) 0
            . VU.unsafeAccumulate (+) (VU.replicate 0x10000 0)
            $ VU.map ((, 1) . mask k) v
      res <- VUM.unsafeNew $ VU.length v
      VU.forM_ v $ \x -> do
        let !masked = mask k x
        i <- VUM.unsafeRead pref masked
        VUM.unsafeWrite pref masked $ i + 1
        VUM.unsafeWrite res i x
      return res
{-# INLINE radixSort32 #-}

compress :: VU.Vector Int -> VU.Vector Int
compress vec = VU.create $ do
  mvec <- VUM.unsafeNew (VU.length vec)
  VU.mapM_ (\(i, x) -> VUM.unsafeWrite mvec (x .&. 0xffffffff) i) . VU.postscanl' (\(!i, !x) y ->
        if x .>>. 32 == y .>>. 32
          then (i, y)
          else (i + 1, y)
      ) (-1, -1)
    . radixSortInt
    $ VU.imap (\i x -> x .<<. 32 .|. i) vec
  return mvec
{-# INLINE compress #-}

class Word64Encode a where
  encode64 :: a -> Word64
  decode64 :: Word64 -> a
  encodeNonNegative64 :: a -> Word64
  encodeNonNegative64 = encode64
  decodeNonNegative64 :: Word64 -> a
  decodeNonNegative64 = decode64

instance Word64Encode Int where
  encode64 x = unsafeCoerce $ x + 0x3fffffffffffffff
  decode64 x = unsafeCoerce x - 0x3fffffffffffffff
  encodeNonNegative64 = unsafeCoerce
  decodeNonNegative64 = unsafeCoerce

instance Word64Encode (Int, Int) where
  encode64 (x, y) = unsafeCoerce
    $ (x + 0x3fffffff) .<<. 31 .|. (y + 0x3fffffff)
  decode64 xy = unsafeCoerce (x, y)
    where
      !x = xy .>>. 31 - 0x3fffffff
      !y = (xy .&. 0x7fffffff) - 0x3fffffff
  encodeNonNegative64 (x, y) = unsafeCoerce $ x .<<. 31 .|. y
  decodeNonNegative64 xy     = unsafeCoerce (x, y)
    where
      !x = xy .>>. 31
      !y = xy .&. 0x7fffffff

instance Word64Encode (Int, Int, Int) where
  encode64 (x, y, z) = unsafeCoerce $ ((x + 0xfffff) .<<. 21 .|. (y + 0xfffff)) .<<. 21 .|. (z + 0xfffff)
  decode64 xyz = unsafeCoerce (x, y, z)
    where
      !x = xyz .>>. 42 - 0xfffff
      !y = (xyz .>>. 21 .&. 0x1fffff) - 0xfffff
      !z = xyz .&. 0x1fffff - 0xfffff
  encodeNonNegative64 (x, y, z) = unsafeCoerce $ (x .<<. 21 .|. y) .<<. 21 .|. z
  decodeNonNegative64 xyz = unsafeCoerce (x, y, z)
    where
      !x = xyz .>>. 42
      !y = xyz .>>. 21 .&. 0x1fffff
      !z = xyz .&. 0x1fffff

stream :: Monad m => Int -> Int -> VFSM.Stream m Int
stream !l !r = VFSM.Stream step l
  where
    step x
      | x < r     = return $ VFSM.Yield x (x + 1)
      | otherwise = return $ VFSM.Done
    {-# INLINE [0] step #-}
{-# INLINE [1] stream #-}

rep :: Monad m => Int -> (Int -> m ()) -> m ()
rep n = flip VFSM.mapM_ (stream 0 n)
{-# INLINE rep #-}

infixl 8 .<<., .>>.
(.<<.) :: Bits b => b -> Int -> b
(.<<.) = unsafeShiftL
{-# INLINE (.<<.) #-}
(.>>.) :: Bits b => b -> Int -> b
(.>>.) = unsafeShiftR
{-# INLINE (.>>.) #-}
fi :: Int -> Integer
fi = fromIntegral
{-# INLINE fi #-}
fI :: Integer -> Int
fI = fromInteger
{-# INLINE fI #-}
ctz :: FiniteBits fb => fb -> Int
ctz = countTrailingZeros
{-# INLINE ctz #-}
powModInt :: Int -> Int -> Int -> Int
powModInt !a !n !mo = fI $ GMP.powModInteger (fi a) (fi n) (fi mo)
{-# INLINE powModInt #-}
type CParser a = StateT BSC8.ByteString Maybe a
runCParser :: CParser a -> BSC8.ByteString -> Maybe (a, BSC8.ByteString)
runCParser = runStateT
{-# INLINE runCParser #-}
int :: CParser Int
int = coerce $ BSC8.readInt . BSC8.dropWhile isSpace
{-# INLINE int #-}
seqInput :: Int -> IO (VU.Vector Int)
seqInput n = VU.unfoldrN n (runCParser int) <$> BSC8.getLine
{-# INLINE seqInput #-}