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.
def check(s):
    index=0
    n=len(s)
    if(n<=3):return False
    for i in range(n-1):
        if(s[i]=='A' and s[i+1]=='B'):
            index=i+1
            break
    if(index==n-1):return False
    for i in range(index+1,n-1):
        if(s[i]=='B' and s[i+1]=='A'):
            return True
    return False
    
s=input()
if(check(s)):print('YES')
else:print('NO')