import sys
read=sys.stdin.buffer.read
readline=sys.stdin.buffer.readline
readlines=sys.stdin.buffer.readlines

n=int(readline())
dp=[0]*(n+1)
for i in range(2, n+1):
    st=set()
    if i%2==0:
        st.add(0)
    else:
        st.add(dp[i//2]^dp[i//2+1])
    if i%3==0 or i%3==2:
        st.add(dp[i//3])
    else:
        st.add(dp[i//3+1])
    for x in range(3):
        if x not in st:
            dp[i]=x
            break
if dp[n]:
    print('A')
else:
    print('B')