n = int(input())
if n == 1:
    print('B')
    exit()
grundy = [-1]*(n+1)
grundy[0] = 0
grundy[1] = 0
for i in range(2, n+1):
    S = set()
    if i%2 == 0:
        g = grundy[i//2]^grundy[i//2]
        S.add(g)
    else:
        g = grundy[(i-1)//2]^grundy[(i-1)//2+1]
        S.add(g)
    if i%3 == 0:
        g = grundy[i//3]^grundy[i//3]^grundy[i//3]
        S.add(g)
    elif i%3 == 1:
        g = grundy[(i-1)//3]^grundy[(i-1)//3]^grundy[(i-1)//3+1]
        S.add(g)
    else:
        g = grundy[(i-1)//3]^grundy[(i-1)//3+1]^grundy[(i-1)//3+1]
        S.add(g)
    g = 0
    while True:
        if g not in S:
            break
        else:
            g += 1
    grundy[i] = g
#print(grundy)
if grundy[n]:
    print('A')
else:
    print8('B')