import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

n, d = MI()
if n > d:
    print('A'*d + 'C'*(n-d))
elif n == d:
    print('A'*n)
else:
    print('A'*(2*n-d) + 'B'*(d-n))