box=int(input())
list1=[]
line=input()
line=line.rstrip().split(" ")
win=0
for i in range(len(line)):
    if int(line[i])>=3:
        win=1
        break
    elif int(line[i])==0:
        pass
    elif int(line[i])==1 or int(line[i])==2:
        list1.append(int(line[i]))

c1=list1.count(1)
c2=list1.count(2)
if win==1:
    print("B")
elif c2>=2:
    print("B")
elif c2==1:
    if c1%2==1:
        print("A")
    else:
        print("B")
elif c1%2==0:
    print("B")
else:
    print("A")