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 main():

    s = input()

    found = False
    index1 = s.find("AB")
    index2 = s.find("BA")
    while index1 != -1 and index2 != -1:
        if index1+1 != index2 and index2+1 != index1:
            found = True
            break
        s = s.replace("AB", "")
        s = s.replace("BA", "")
        index1 = s.find("AB")
        index2 = s.find("BA")
    
    print("YES") if found else print("NO")

    return 0

if __name__ == "__main__":
    main()