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
n=len(s)
fab=False
fba=False
e=-1
while i<n-1:
    if s[i:i+2]=='AB' and not fab:
        if i!=e:
            fab=True
            e=i+1
        
    elif s[i:i+2]=='BA' and not fba:
        if i!=e:
            fba=True
            e=i
        
    i+=1
if fab and fba:print("YES")
else:print('NO')
        