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.
s = input()
x1 = s.find("AB")  # FIRST OCCURRENCE OF AB IS x1
x2 = s.find("BA", x1 + 2)  # OCCURRENCE of BA FROM x1+2 POSITION
y1 = s.find("BA")
y2 = s.find("AB", y1 + 2)

if (x1 != -1 and x2 != -1) or (y1 != -1 and y2 != -1):
    print("YES")
else:
    print("NO")