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 = str(input())
a = False
b = False
i = 0
while i < (len(s)-1) :
    if s[i] == "A" and s[i+1] == "B":
        a = True
        i += 2
    elif s[i] == "B" and s[i+1] == "A":
        b = True
        i += 2
    else:
        i += 1
if a and b:
    print("YES")
else:
    print("NO")