import Data.Char
import Data.Word

main :: IO ()
main = do
    xs <- getLine
    let n :: Word32
        n = read xs
    let solve :: Word32 -> [Char] -> [Char]
        solve tmp xs = let a = tmp `div` 26 in if a == 0 then (chr (fromI (96+tmp`mod`26))):xs else solve a ((chr (fromI (96+tmp`mod`26))):xs)
    putStrLn $ solve n []
fromI :: Word32 -> Int
fromI = fromIntegral