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()
index1= string.find("AB")
index2= string.find("BA",index1+2)
index3= string.find("BA")
index4= string.find("AB",index3+2)

if index1 != -1 and index2 != -1:
    print("YES")

if index3 != -1 and index4 != -1:
    print("YES")

else:
    print("NO")