n = int(input())
g = [0]*(n+1)
for i in range(2,n+1):
    s = set()
    s.add(g[i//2]^g[i-i//2])
    s.add(g[i//3]^g[(i+1)//3]^g[(i+2)//3])
    for j in range(n+1):
        if j not in s:
            g[i] = j
            break
print("A" if g[n] else "B")