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()
n= len(s)
i = 0
f = 1
p = -1
while i < n - 1:
    if p == -1:
        if s[i] == 'A' and s[i+1] =='B':
            i+=1
            p = 0
        elif s[i] =='B' and s[i+1]=='A':
            i+=1
            p=1
    elif p == 1:
        if s[i] == 'A' and s[i+1] =='B':
            p = 2
            break
    elif p == 0:
        if s[i] == 'B' and s[i+1] =='A':
            p = 2
            break
if p == 2:
    print("YES")
else:
    print("NO")