content: -- https://onlinejudge.u-aizu.ac.jp/solutions/problem/ITP2_1_B/review/3600263/rabbisland/Haskell
  import Control.Monad ( foldM_, replicateM )
  import Data.ByteString.Char8 (ByteString)
  import qualified Data.ByteString.Char8 as B
  import Data.List ( unfoldr )
  import Data.Char (isSpace)
  import Data.Sequence ((<|), (|>), ViewL(..), ViewR(..), Seq)
  import qualified Data.Sequence as Sq
  
  main :: IO ()
  main = do
    q <- readLn
    replicateM q f >>= solve
    where f = fmap (readil B.readInt) B.getLine
  
  solve :: [[Int]] -> IO ()
  solve = foldM_ f Sq.empty where
    f sq [0, d, x] = push sq d x
    f sq [1, p] = do
      randomAccess sq p >>= print
      return sq
    f sq [2, d] = pop sq d
    f _ _ = error "not come here"
  
  push :: Seq Int -> Int -> Int -> IO (Seq Int)
  push sq d x
    | d == 0 = return $ x <| sq
    | otherwise = return $ sq |> x
  
  randomAccess :: Seq Int -> Int -> IO Int
  randomAccess sq p = return $ Sq.index sq p
  
  pop :: Seq Int -> Int -> IO (Seq Int)
  pop sq d
    | d == 0 = let (_ :< sq') = Sq.viewl sq in return sq'
    | otherwise = let (sq' :> _) = Sq.viewr sq in return sq'
  
  readil :: Integral a =>  (ByteString -> Maybe (a, ByteString)) -> ByteString -> [a]
  readil f = unfoldr $ \s -> do
    (n, s') <- f s
    return (n, B.dropWhile isSpace s')
  
  