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()

i = 1
found_AB = False
found_BA = False

while i < len(s):
    if s[i] == 'B' and s[i-1] == 'A':
        found_AB = True
        i += 2
        continue

    if s[i] == 'A' and s[i-1] == 'B':
        found_BA = True
        i += 2
        continue

    i += 1

if found_BA and found_AB:
    print("YES")
else:
    print("NO")