def calcs(x,y,ax,ay,bx,by) ((ax-x)*(by-y)-(bx-x)*(ay-y))/2.0 end
def inpf() a=gets.chomp.split(" ").map(&:to_f)end
def inps() a=gets.chomp.split(" ")end  
def copy(a) Marshal.load(Marshal.dump(a)) end
def kaizyo(n)(n < 2)? 1 : (2..n).inject(:*) end
def scount(a) b=na(a.max+1);a.each{|n|b[n]+=1};return b end
def na(n=0,d=0) Array.new(n,d)end
def na2(n=0,m=0,d=0) Array.new(n){Array.new(m,d)}end
def na3(n=0,m=0,l=0,d=0) Array.new(n){Array.new(m){Array.new(l,d)}}end
def bit(n) n.to_s(2).split("").map(&:to_i) end
def inp() a=gets.chomp.split(" ").map(&:to_i)end
n,m=inp
while(true)
if(n==m)
  puts "A" * n
  break
elsif(n*2==m)
  puts "B" * n
  break
elsif(m == 0)
  puts "C" * n
  break
else
  print "A"
  n-=1
  m-=1
end
end
=begin
=end