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.
a=input()
count1t1=a.count("AB")
t1=a.replace("AB","",1)
count2t1=t1.count("BA")

count1t2=a.count("BA")
t2=a.replace("BA","",1)
count2t2=t2.count("AB")
if((count1t1>=1 and count2t1>=1 )or( count1t2>=1 and count2t2>=1 )):
    print("YES")
else:
    print("NO")