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)


{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE BangPatterns #-}

module Main where

import Debug.Trace
--import Data.List
--import qualified Data.Set.Strict as Set
--import qualified Data.Map.Strict as Map

main :: IO ()
main = do
  a <- read <$> getLine
  --a `traceShow`
  putStrLn $ solve a

solve :: Int -> String
solve a = build a ""

char_range :: Int
char_range = fromEnum 'z' - fromEnum 'a' + 1

char_start :: Int
char_start = fromEnum 'a'

build :: Int -> String -> String
build a s
  -- | a <= 0 = s `traceShow` s
  | a <= 0 = s
  -- | otherwise = (a, m, d, s) `traceShow` build d ((toEnum (char_start + m)):s)
  | otherwise = build d ((toEnum (char_start + m)):s)
  where
    m = (a - 1) `mod` char_range
    d = (a - 1 - char_range) `div` char_range + 1


--toEnum (fromEnum 'a' + 2) :: Char