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() 
x =  string.find("AB")
t = string.find("BA") 
if x == t ==-1 : 
        print("NO")
elif string[x+2 : x+3 ] == "B" :
        print('NO')
elif string[x+2 : x+3] == "A" :
        print("NO")
else: 
        print("YES")