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.
word = str(input())

indices = []
# if "AB" in word and "BA" in word:
for i in range(len(word)):
    try:
        if word[i] + word[i+1] == "AB" or word[i] + word[i+1] == "BA" and i not in indices and (i+1) not in indices:
            indices.append(i)
            indices.append(i+1)   
    except IndexError:
        break;
if len(indices) >= 4:
    print("YES")
else:
    print("NO")
