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 solver():
    s = input()
    for i in range(len(s)-1):
        if s[i] == 'A' and s[i+1] == 'B' and 'BA' in s[i+2:]:
            return "YES"
        elif s[i] == 'B' and s[i+1] == 'A' and 'AB' in s[i+2:]:
            return "YES"
    return "NO"

print(solver())