import sys

n=int(raw_input())
if n==1:
 print 'B'
 sys.exit()
g=[0 for i in xrange(n+1)]
g[2]=1
for i in xrange(3,n+1):
 s=[]
 if i%2==0: s.append(0)
 if i%2==1: s.append(g[i/2]^g[i/2+1])
 if i%3==0: s.append(g[i/3])
 if i%3==1: s.append(g[i/3+1])
 if i%3==2: s.append(g[i/3])
 
 while s.count(g[i]):
  g[i]+=1
  
if g[n]==0:
 print 'B'
else:
 print 'A'