bswap [x] = [x]
bswap (x:y:zs)
    | x < y     = y : bswap (x:zs)
    | otherwise = x : bswap (y:zs)

bsort [] = []
bsort xs = y : bsort ys
    where
        (y:ys) = reverse $ bswap xs

median :: [Int] -> Int -> Double
median [x] _ = fromIntegral (x :: Int) :: Double
median l n   | n `mod` 2 == 0   = l_even (l !! n') (l !! (n' + 1))
             | otherwise        = fromIntegral (l !! n' :: Int) :: Double
    where
        n' = floor $ (fromIntegral (n - 1 :: Int)) / 2.0    -- 小数点以下切り捨て 3.5 -> 3
        l_even x x' = (fromIntegral ((x + x') :: Int)) / 2.0 :: Double

main = do
    str1 <- getLine
    str2 <- getLine
    let
        w = words str2
        n = read str1
        l = map read w :: [Int]
        bl = bsort l :: [Int]
        result = median bl n
    print result