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

grundy :: Int -> Int
grundy 0 = 0
grundy 1 = 0
grundy n = mex $ [foldl1 xor [dp !! (i`div`2) | i<-[n,n+1]]] ++ (if n<3 then [] else [foldl1 xor [dp !! (i`div`3) | i<-[n..n+2]]])

dp :: [Int]
dp = [grundy i | i <- [0..]]

main = do
  l <- (read::String->Int) <$> getLine
  putStrLn $ if dp!!l /= 0 then "A" else "B"