s = input().split()
n = int(s[0]) #文字列の数
d = int(s[1]) #穴の個数
a = ""

while d > 0:
    if d <= n:
        a = "A" + a
        d -= 1
        n -= 1
    else:
        a += "B"
        d -= 2
        n -= 1

for i in range(n):
    a += "C"

print(a)