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.
l = input()

i = 0

a = []

while i < len(l) - 1:
    if l[i] + l[i + 1] == 'BA' or l[i] + l[i + 1] == 'AB':
        a.append(l[i] + l[i + 1])
        i += 1

    i += 1

if set(a) == {'AB', 'BA'}:
    print("YES")
else:
    print("NO")