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().lower()+"ghjkl"
ab = 0
ba = 0
ab1 = s.find("ab")+1
ba1 = s.replace("ab", "-", 1).find("ba")+1
ba2 = s.find("ba")+1
ab2 = s.replace("ba", "-", 1).find("ab")+1

if ab1*ba1+ba2*ab2 !=0:
    print("YES")
else:
    print("NO")