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()
n=len(s)
x=s.find("AB")
y=s.find("BA")
if x!=-1 and y!=-1:
    p_=s[x+2:].find("BA")
    p=s[y+2:].find("AB")
    if p_!=-1 or p!=-1:print("YES")
    else: print("NO")
else:print("NO")