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()
t = 0
for i in range(len(s)-1):
    if s[i] == 'A' and s[i+1] == 'B':
        t = 1
        break
    if s[i] == 'B' and s[i+1] == "A":
        t = 2
        break
if t == 2:
    if "BA" in s:
        s = s.replace("BA", "--", 1)
        if 'AB' in s:
            print("YES")
        else:
            print("NO")
    else:
        print('NO')
if t == 1:
    if "AB" in s:
        s = s.replace("AB", "--", 1)
        if 'BA' in s:
            print("YES")
        else:
            print("NO")
    else:
        print('NO')
