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()
yes = False
leftMostAB = -1
leftMostBA = -1
rightMostAB = -1
rightMostBA = -1
for i in range(len(s)-1):
    if s[i:i+2] == "AB":
        leftMostAB = i
    if s[i:i+2] == "BA":
        leftMostBA = i

for i in range(len(s)-2,-1,-1):
    if s[i:i+2] == "AB":
        rightMostAB = i
    if s[i:i+2] == "BA":
        rightMostBA = i
if leftMostAB+1 < rightMostBA or leftMostBA+1 < rightMostAB:
    print("YES")
else:
    print("NO")