Problem:
Score : 300 points

Problem Statement

1000000000000001 dogs suddenly appeared under the roof of Roger's house, all of which he decided to keep. The dogs had been numbered 1 through 1000000000000001, but he gave them new names, as follows:

the dogs numbered 1,2,\cdots,26 were respectively given the names a, b, ..., z;

the dogs numbered 27,28,29,\cdots,701,702 were respectively given the names aa, ab, ac, ..., zy, zz;

the dogs numbered 703,704,705,\cdots,18277,18278 were respectively given the names aaa, aab, aac, ..., zzy, zzz;

the dogs numbered 18279,18280,18281,\cdots,475253,475254 were respectively given the names aaaa, aaab, aaac, ..., zzzy, zzzz;

the dogs numbered 475255,475256,\cdots were respectively given the names aaaaa, aaaab, ...;

and so on.

To sum it up, the dogs numbered 1, 2, \cdots were respectively given the following names:

a, b, ..., z, aa, ab, ..., az, ba, bb, ..., bz, ..., za, zb, ..., zz, aaa, aab, ..., aaz, aba, abb, ..., abz, ..., zzz, aaaa, ...

Now, Roger asks you:

"What is the name for the dog numbered N?"

Constraints

N is an integer.

1 \leq N \leq 1000000000000001

Input

Input is given from Standard Input in the following format:

N

Output

Print the answer to Roger's question as a string consisting of lowercase English letters.

Sample Input 1

2

Sample Output 1

b

Sample Input 2

27

Sample Output 2

aa

Sample Input 3

123456789

Sample Output 3

jjddja

Solution in Haskell (GHC 8.8.3) (judge verdict: Accepted)

import qualified Data.Vector.Unboxed as V
import qualified Data.ByteString.Char8 as BS
import Data.Char
import Data.List
import Data.Maybe

main = do
  n <- readLn  :: IO Integer
  putStrLn $ solve n

solve n = map (chr .(+ ord 'a') . fromIntegral) $ go n []
  where
    go n ns
      | n == 0 = ns
      | otherwise =
          let (p, q) = divMod (n-1) 26
          in go p (q:ns)
  
getInt :: IO Int
getInt = readLn

second :: (b -> c) -> (a, b) -> (a, c)
second f (a, b) = (a, f b)

readInt :: BS.ByteString -> Maybe (Int, BS.ByteString)
readInt = fmap (second BS.tail) . BS.readInt

readIntVec :: Int -> IO (V.Vector Int)
readIntVec n = V.unfoldrN n readInt <$> BS.getLine

readIntList :: IO [Int]
readIntList = map (fst . fromJust . BS.readInt) . BS.words <$> BS.getLine

readIntPair :: IO (Int, Int)
readIntPair = do
  v <- readIntVec 2
  return (v V.! 0, v V.! 1)