n = gets.chomp!.to_i
abort unless 1 <=n && n<=150

cstr = gets.chomp!
abort unless cstr =~ /^\d+(?: \d+)*$/
abort unless !gets


c = cstr.split.map(&:to_i)

count = Array.new(4,0)

c.each{|e| count[ [3,e].min ] += 1 }


if count[1].odd? && count[2]<=1 && count[3]==0
    puts 'A'
else
    puts 'B'
end