import qualified Data.ByteString.Char8 as BS
import Data.Char
import Data.Maybe

readInt = fst . fromJust . BS.readInt

getInt = readInt <$> BS.getLine

calc n s
  | n <= 26 = (chr (ord 'a' + n - 1)) : s
  | otherwise = calc d ((chr (ord 'a' + m - 1)) : s)
  where
    m = n `mod` 26
    d = n `div` 26

main = do
  n <- getInt
  putStrLn $ calc n ""
