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()
ab = set()
ba = set()
for i in range(1,len(s)):
    if s[i]=='B' and s[i-1] == 'A':
        ba.add(i-1)
    if s[i]=='A' and s[i-1] == 'B':
        ab.add(i-1)
for a in ab:
    for b in ba:
        if abs(a-b)>1:
            print('YES')
            exit()
print('NO')
            
            
        
        
    
    
    
