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.
from sys import stdin,stdout
from collections import Counter,defaultdict 

def I(): return int(stdin.readline())
def II(): return map(int, stdin.readline().split())
def IL(): return list(map(int, stdin.readline().split()))
def SIL(): return sorted(map(int, stdin.readline().split()))



def solve():
    
    # write your code here 
    word = input()
    n = len(word)

    if  n < 2:
        return 'YES'
    for i in range(1,n-1):
        if word[i-1] == word[i+1]:
            return "NO"
    
    return "YES"
    
    
    
    
    
    
    
    
    

print(solve())
