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.
string = input()
found_ab = False
found_ba = False
ab_indices = []
ba_indices = []

for i in range(len(string) - 1):
    if string[i:i+2] == "AB":
        found_ab = True
        ab_indices.append(i)
    if string[i:i+2] == "BA":
        found_ba = True
        ba_indices.append(i)

non_overlapping = False
for ab_index in ab_indices:
    for ba_index in ba_indices:
        if abs(ab_index - ba_index) > 1:
            non_overlapping = True
            break

    if non_overlapping:
        break

if found_ab and found_ba and non_overlapping:
    print("YES")
else:
    print("NO")
