-- Try yukicoder
-- author: Leonardone @ NEETSDKASU

main = putStrLn . solve . map read . words =<< getLine

solve [n, d] = reverse $ hoge "" n d where
    hoge s 0 0 = s
    hoge s n 0 = replicate n 'C' ++ s
    hoge s 0 d = fuga "" s d
    hoge s n d = hoge ('A':s) (n-1) (d-1)
    fuga t s 0 = t ++ s
    fuga t (_:ss) d = fuga ('B':t) ss (d-1)