import sys,collections
sys.setrecursionlimit(10**7)

def Is(): return [int(x) for x in sys.stdin.readline().split()]
def Ss(): return sys.stdin.readline().split()
def I(): return int(sys.stdin.readline())
def S(): return input()

n = I()
cs = Is()
count = cs.count(1)
if count % 2 == 1 and max(cs) <= 2:
    print("A")
else:
    print("B")