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()
a =[]
b = []
for i in range(len(s) - 1):
    if s[i] == "A" and s[i + 1] == "B":
        a.append(i)
    if s[i] == "B" and s[i + 1] == "A":
        b.append(i)

if len(a) > 0 and len(b) > 0 and (min(a) < max(b) - 1 or min(b) < max(a)):
    print("YES")
else:
    print("NO")

