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.
a=input()
m=1
n=1
if 'AB' in a:
    b=a[a.find('AB')+2:]
    if 'BA' in b:
        m=2
if 'BA' in a:
    b=a[a.find('BA')+2:]
    if 'AB' in b:
        n=2
if m==2 or n==2:
    print("YES")
else:
    print("NO")