import sequtils,strutils
var
    N = stdin.readline.parseInt
    C = stdin.readline.split.map(parseInt)
    cnt1 = 0
    cnt2 = 0
    flag : bool
    
    
for n in 0..<N:
    if C[n] == 0:
        continue
    cnt1 = 0
    cnt2 = 0
    C[n] -= 1
    
    for c in C:
        if c == 1:
            cnt1 += 1
        if c >= 2:
            cnt2 += 1
    if cnt2 == 0 and cnt1 mod 2 == 0:
        flag = true
    
    C[n] += 1

if flag:
    echo "A"
else:
    echo "B"