import math

n = int(input())

grundy_ls = [-1] * (n + 1)
grundy_ls[1] = 0

def grundy(n):
    if grundy_ls[n] >= 0:
        return grundy_ls[n]
    
    g_set = set()
    g_set.add(grundy(n // 2) ^ grundy(math.ceil(n / 2)))
    if n >= 3:
        g_set.add(grundy(n // 3) ^ grundy(round(n / 3)) ^ grundy(math.ceil(n / 3)))
    
    for i in range(n):
        if not i in g_set:
            grundy_ls[n] = i
            return i

gn = grundy(n)
if gn == 0:
    print('B')
else:
    print('A')