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 = input()
start = -1
count = 0
while True:
    start = s.find("AB", start+1)
    if start == -1:
        break
    count += 1
print(count)
