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().strip()

f1=f2=-1

f = s.find("AB")

if f != -1:
    f1 = s.find("BA",f+2)

f = s.find("BA")

if f != -1:
    f2 = s.find("AB",f+2)

print("YNEOS" [f1 == f2 == -1 :: 2])
