n=int(input())

from functools import lru_cache
@lru_cache(maxsize=None)
def grundy(n):
    if n==1:
        return 0
    
    SET=set()

    SET.add(grundy(n//2)^grundy(n-n//2))

    if n>=3:
        if n%3==0:
            SET.add(grundy(n//3))
        elif n%3==1:
            SET.add(grundy(n//3+1))
        else:
            SET.add(grundy(n//3))

    for i in range(1000):
        if i in SET:
            continue
        else:
            return i

if grundy(n)!=0:
    print("A")
else:
    print("B")