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.
str = input()
ab1 = str.find("AB")
ba1 = str.rfind("BA")
ab2 = str.rfind("AB")
ba2 = str.find("BA")
if ab1 == -1 or ba1 == -1 or ab2 == -1 or ba2 == -1:
    print("NO")
elif abs(ab1 - ba1) > 1 or abs(ab2 - ba2) > 1:
    print("YES")
else:
    print("NO")