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 = 0
ab = False
ba = False
while i < len(s):
    if s[i:i+2] == "AB":
        ab = True
        i += 1
    elif s[i:i+2] == "BA":
        ba = True
        i += 1
    i += 1
    if ab and ba:
        break
if ab and ba:
    print("YES")
else:
    print("NO")