def grundy(x):
    if dp[x] >= 0:
        return dp[x]
    tmp = []
    a = 0
    if x % 2 == 0:
        tmp.append(0)
    else:
        tmp.append(grundy(x//2) ^ grundy(x//2+1))
    if x % 3 == 0 or x % 3 == 2:
        tmp.append(grundy(x//3))
    else:
        tmp.append(grundy(x//3 + 1))
    for i in range(3):
        if i not in tmp:
            dp[x] = i
            return i

N = int(input())
dp = [-1] * (N + 1)
dp[0] = dp[1] = 0
if grundy(N) == 0:
    print("B")
else:
    print("A")