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.
import sys
input = lambda: sys.stdin.readline().rstrip()

S = input()
N = len(S)
INF = float('inf')
ab,ba=INF,INF
ans = 'NO'
for i in range(N-1):
    if S[i:i+2]=='AB':
        ab = min(ab, i)
        if ba!=INF and i-ba>=2:
            ans = 'YES'
            break
    elif S[i:i+2]=='BA':
        ba = min(ba, i)
        if ab!=INF and i-ab>=2:
            ans = 'YES'
            break
            
print(ans)
        
        
        