from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math,time,random
input = sys.stdin.readline

N = int(input())


mem = [-1]*(N+1)
def f(x):
    if mem[x]!=-1:
        return mem[x]
    if x%2==0:
        mem[x] = 1
        return 1
    
    if x==1:
        mem[x] = 0
        return mem[x]
    
    X = []
    n = x//2
    if n%2==0:
        X.append(f(n+1))
    else:
        X.append(f(n))

    n = x//3
    if x%3==0:
        X.append(f(n))
    elif x%3==1:
        X.append(f(n+1))
    else:
        X.append(f(n))
    mem[x] = 1 - min(X)
    return mem[x]

if f(N):
    print('A')
else:
    print('B')