n = gets.to_i
c_list = gets.split.map(&:to_i)

gt2 = c_list.count {|c| c > 2}
two = c_list.count(2)
one = c_list.count(1)

if gt2 > 0 or two > 1
  puts 'B'
elsif (one + two * 2) % 2 == 0
  puts 'B'
else
  puts 'A'
end