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()
a1, a2 = 0, 0
a3, a4 = 0, 0
if 'AB' in s and 'BA' in s:
    for i in range(len(s)-1):
        if s[i] + s[i+1] == 'AB':
            a1, a2 = i, i+1
            break
    for i in range(len(s) - 1, 0, -1):
        if s[i-1] + s[i] == 'BA':
            a3, a4 == i-1, i
            break
    if a1 != a4 and a2 != a3:
        print('YES')
    else:
        print('NO')
else:
    print('NO')