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();lenn=len(s)
p=s.index("AB");p_=s.index("BA")
x=0;y=0
if p+2<lenn:
    x=s[p+2:].count("BA")
if p_+2<lenn:
    y=s[p_+2:].count("AB")
if x>0 or y>0:print("YES")
else:print("NO")