N,hole = (int(n) for n in input().split(" "))
answer = ""
Anum,Bnum,Cnum =0,0,0
while N > 0:
    if hole - N >= 1:
        Bnum += 1
        hole -= 2
    elif hole - N == 0:
        Anum += 1
        hole -= 1
    else:
        Cnum += 1
    N -= 1
answer = "A" * Anum + "B" * Bnum + "C" * Cnum
print(answer)