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.
x=input()
a1="AB"
a2="BA"
a3="BAAB"
a4="ABBA"
if a1 in x and a2 in x:
   if a3 in x or a4 in x:
    
            print("NO")
   else:
        print("YES")
    
else:
    print("NO")