N=int(raw_input())

dp=[0 for i in range(101)]
dp[1]=0
dp[2]=1
for i in range(3,N+1):
    half=dp[i/2]^dp[i-i/2]
    tri=dp[i/3]^dp[(i-i/3)/2]^dp[i-i/3-(i-i/3)/2]
    for j in range(3):
        if j!= half and j!= tri:
            dp[i]=j
            break
    #print i,half,tri,i/3,(i-i/3)/2,i-(i-i/3)/2,dp[i]
if dp[N] == 0:
    print "B"
else:
    print "A"