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.
string = input()
 
def find_substring(start, string, substring):
    for i in range(start, len(string)-1):
        if string[i: i+len(substring)] == substring:
            return i
    return -1



def solve(sub_input):


    index = find_substring(0, sub_input, 'AB')
    if index!=-1:
        index = find_substring(index + 2, sub_input, 'BA')
        if index!=-1:
            return 'YES'

    index = find_substring(0, sub_input, 'BA')
    if index != -1:
        index = find_substring(index + 2, sub_input, 'AB')
        if index != -1:
            return 'YES'

    return 'NO'
 
print(solve(string))