import Control.Applicative
import Data.List
import Data.Bits
import Data.Array

mex :: [Int] -> Int
mex list = mex_sub 0 $ sort list
  where
    mex_sub n [] = n
    mex_sub n (x:xs)
      | n == x = mex_sub (n+1) xs
      | otherwise = n

nextGrundy :: Array Int Int -> Int -> [Int]
nextGrundy gr n = [foldl xor 0 [gr ! (i`div`2) | i<-[n,n+1]]] ++ (if n<3 then [] else [foldl xor 0 [gr ! (i`div`3) | i<-[n..n+2]]])

main = do
  l <- (read::String->Int) <$> getLine
  let gr = array (1,l) $ (1,0):[(i,(mex $ nextGrundy gr i))|i<-[2..l]]
  putStrLn $ if gr!l /= 0 then "A" else "B"