n=gets.to_i
c=gets.split(" ").map(&:to_i)
n=c.length-c.count(0)
if c.max>2 then
    puts "B"
elsif c.count(2)>1 then
    puts "B"
elsif c.count(2)==1 then
    if n%2==0 then
        puts "A"
    else
        puts "B"
    end
else
    if n%2==0 then
        puts "B"
    else
        puts "A"
    end
end