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 solve(s):
    l = []
    for i in range(len(s) - 1):
        l.append(s[i: i + 2])
    if(l.count('AB') == 0 or l.count("BA")):
        return "NO"
    for i in range(len(l) - 1):
        if(((l[i] == 'AB') and l[i+1] == 'BA') or ((l[i+1] == 'AB') and (l[i] == 'BA'))):
            return "NO"
    return "YES"

s = input()
print(solve(s))
