#yuki_582

n=int(raw_input())
c=map(int,raw_input().split())

c1=[]
for x in c:
 if x!=0:
  c1.append(x)
cc=c1.count(1)
if (cc%2 and len(c1)==cc) or (cc%2 and c1.count(2)==1 and len(c1)==cc+1):
 print 'A'
else: 
 print 'B'