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()
x = s.find('AB')
y = s.find('BA')
if x == -1 or y == -1:
    print('NO')
elif x + 1 < y or y + 1 < x:
    print('YES')
else:
    if x + 2 < len(s) and s[x + 2:].find('BA') != -1:
        print('YES')
    elif y + 2 < len(s) and s[y + 2:].find('AB') != -1:
        print('NO')