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 = list(input())
a = False
b = False
for i in range(len(s) - 1):
    if not a and s[i] == 'A' and s[i+1] == 'B':
        a = True
        continue
    if not b and s[i] == 'B' and s[i+1] == 'A':
        b = True
        continue
if a and b:
    print("YES")
else:
    print("NO")