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.
a = input()
ab = []
ba = []
for i in range(len(a)-1):
    if a[i:i+2] == "AB":
        ab.append(i)
    if a[i:i+2] == "BA":
        ba.append(i)
if len(ba) != 0 and len(ab) != 0:
    if ba[-1] - ab[0] > 1 or ab[-1] - ba[0] > 1:
        print("YES")
    else:
        print("NO")
else:
    print("NO")