n = int(input())
do = [0]*(n+1)
for i in range(1,n+1):
    se = []
    if i >= 2:
        se.append(do[i//2])
        if i%2 != 0:
            se.append(do[i//2+1])
    if i >= 3:
        se.append(do[i//3])
        if i%3 != 0:
            se.append(do[i//3+1])
    ans = 0
    while ans in se:
        ans+=1
    do[i] = ans
print("B" if do[n] == 0 else "A")