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()

i = 1
AB_B = set()
BA_B = set()

while i < len(s):
    if s[i] == 'B' and s[i-1] == 'A':
        AB_B.add(i)

    if s[i] == 'A' and s[i-1] == 'B':
        BA_B.add(i-1)

    i += 1

if (AB_B.intersection(BA_B) and (AB_B.difference(BA_B) or BA_B.difference(AB_B))) or (AB_B.difference(BA_B) and BA_B.difference(AB_B)):
    print("YES")
else:
    print("NO")