{-# LANGUAGE TypeApplications #-}

import           Control.Monad
import           Control.Applicative
import           Data.List
import           Data.Char
import           Control.Arrow

main = do
  n <- readLn @Int
  putStrLn $ solve n []
 where
  solve 0 str = str
  solve n str =
    let a = chr $ ord 'a' + ((n - 1) `mod` 26)
        m = (n - 1) `div` 26
    in  solve m (a : str)

