n = int(input())

grundy = [0] * (n + 1)
grundy[1] = 0
for i in range(2, n + 1):
    a = i // 2
    b = (i + 1) // 2
    x = grundy[a] ^ grundy[b]

    a = i // 3
    b = (i + 1) // 3
    c = (i + 2) // 3
    y = grundy[a] ^ grundy[b] ^ grundy[c]

    mex = 0
    while mex == x or mex == y:
        mex += 1
    grundy[i] = mex
if grundy[n] == 0:
    print("B")
else:
    print("A")