You are given string *s*. Your task is to determine if the given string *s* contains two non-overlapping substrings "AB" and "BA" (the substrings can go in any order).
The only line of input contains a string *s* of length between 1 and 10<sup class="upper-index">5</sup> consisting of uppercase Latin letters.
s = list(input())
lest = []
for x in range(1,len(s),2):
    lest.append((s[x-1]+s[x]))
print("YES" if "AB" in lest and "BA" in lest else "NO")