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()
n = len(s)
found_ab = found_ba = False

for i in range(n-1):
    if s[i:i+2] == 'AB':
        found_ab = True
        for j in range(i+2, n-1):
            if s[j:j+2] == 'BA':
                found_ba = True
                break
        if found_ab and found_ba:
            break

    elif s[i:i+2] == 'BA':
        found_ba = True
        for j in range(i+2, n-1):
            if s[j:j+2] == 'AB':
                found_ab = True
                break
        if found_ab and found_ba:
            break

if found_ab and found_ba:
    print("YES")
else:
    print("NO")
