#!/usr/bin/python2
# -*- coding: utf-8 -*-
# †
n, d = map(int, raw_input().split())
v = [0] * n

for loop in xrange(2):
    for i in xrange(n):
        if d > 0:
            v[i] += 1
            d -= 1
cand1 = ''.join('CAB'[x] for x in v)
cand2 = cand1[::-1]
res = cand1
if cand1 > cand2:
    res = cand2
print res