gets
c1 = c2 = 0
gets.split.each do |s|
  case s.to_i
  when 0
  when 1
    c1 += 1
  when 2
    c2 += 1
  else
    puts "B"
    exit
  end
end
if c2 > 1 || (c1 + 2 * c2)%2 == 0
  puts "B"
else
  puts "A"
end