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.
string = input().lower()
try:
    index = string.index('ab')
    result = False
    for i in range(len(string)):
        if string[i] == 'b' and string[i + 1] == 'a':
            overlap = abs(i - index)
            if overlap >= 2:
                result = True
                break
    if result:
        print('YES')
    else:
        print('NO')
except ValueError:
    print('NO')