n = gets.to_i
c = gets.split.map(&:to_i).select{|x|x != 0}
n = c.size
sum = (n==0) ? 0 : c.inject(:+)
if sum % 2 == 0
    puts "B"
else
    if c.count(1) == n || (c.count(1) == n - 1 && c.count(2) == 1)
        puts "A"
    else
        puts "B"
    end
end