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 = list(map(lambda q:str(q), input()))
l=len(s)
t=0
for i in range(l-1):
    if s[i]=='A' and s[i+1]=="B":
        t+=1
        s[i+1]='6'
    elif s[i]=='B' and s[i+1]=="A":
        t+=1
        s[i+1]='c'
if t==2:
    print('YES')
else:
    print('NO')