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.
n=input()
z=t=0;
if 'AB' in n:
    z=1;
if 'BA' in n:
    t=1;
if len(n)>=4:
    if z==1 and t==1:
        print('YES');
if len(n)<4:
    print('NO');
