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.
def has(s, s2):
    i = 0
    for i in range(len(s)-1):
        if s[i:i+2] == s2:
            return True
    return False

t = input()
i = 0
res = "NO"
for i in range(len(t)-1):
    if t[i:i+2]=='AB' and has(t[i+2:], 'BA') or \
            t[i:i + 2] == 'BA' and has(t[i + 2:], 'AB') :
        res = "YES"
print(res)