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()

ind1 = s.find("AB")

ind2 = s.find("BA", ind1+(ind1>=0)*2)

if not(ind1 == -1 or ind2 == -1):
    print("YES")

    quit()


ind1 = s.find("BA")

ind2 = s.find("AB", ind1+(ind1>=0)*2)

if not(ind1 == -1 or ind2 == -1):
    print("YES")

    quit()
    
print("NO")