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
p1 = -1
while i < n - 1:
    if p1 == -1:
        if s[i] == 'A' and s[i+1] =='B':
            i+=1
            p1 = 0
    if p1 == 0:
        if s[i] == 'B' and s[i+1] =='A':
            p1 = 2
            break
    i += 1
p2 = -1
i = 0
while i < n - 1:
    if p2 == -1:
        if s[i] == 'B' and s[i+1] =='A':
            i+=1
            p1 = 0
    if p2 == 0:
        if s[i] == 'A' and s[i+1] =='B':
            p2 = 2
            break
    i += 1
if p1 == 2 or p2 == 2:
    print("YES")
else:
    print("NO")