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()
f=0
for i in range(len(s)-1):
    if s[i:i+2]=="AB":
        t=s[:i]+s[i+2:-1]
        if t.count("BA"):
            f=1
print("YES" if f else "NO")