import Control.Monad.ST
import Data.Char
 
 
readInt :: IO Int
readInt = read <$> getLine :: IO Int
 
readIntSplit :: IO [Int]
readIntSplit = map read . words <$> getLine :: IO [Int]
 
readStr :: IO String
readStr = getLine
 
readStrSplit :: IO [String]
readStrSplit = map read . words <$> getLine

solve :: String -> String
solve "ABC" = "ARC"
solve "ARC" = "ABC"

main = do
  s <- readStr
  putStrLn $ solve s