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 = input()
while "AB" in s or "BA" in s:
    if "AB" in s:
        s = s.replace("AB", "", 1)
    if "BA" in s:
        s = s.replace("BA", "", 1)
if "A" in s or "B" in s:
    print("NO")
else:
    print("YES")