-- yukicoder My Practice
-- author: Leonardone @ NEETSDKASU

main = readLn >>= print . g 6 . f 9 . f 4 where
    f k x
        | m > 0     = x
        | otherwise = f k d
        where (d, m) = divMod x k
    g i x
        | x < k2     = f k1 x
        | otherwise = g (i + 6) $ f k2 $ f k1 x
        where
            k1 = (i - 1) * (i - 1)
            k2 = (i + 1) * (i + 1)