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()
bul = 'NO'
for i in range(len(s)-2):
    if len(s) < 4:
        bul = 'NO'
        break
    if s[i:i+2] == 'AB':
        if s.find('BA', i+2, len(s)) != -1:
            bul = 'YES'
            break
    if s[i:i+2] == 'BA':
        if s.find('AB', i+2, len(s)) != -1:
            bul = 'YES'
            break
print(bul)