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()
i = 0
a,b = 0,0
n = len(s)

while i<n:
    if s[i:i+2] == 'AB' and not a: 
        a = 1
        i+=2
    elif s[i:i+2] == 'BA' and not b: 
        b = 1
        i+=2
    else : i+=1

if a and b : print("YES")
else : print("NO")