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() 
flag_ab = False
flag_ba = False
for i in range(0 , len(string) ,2): 
    if string[i : i+2] == "AB" : 
        flag_ab =True 
    elif string[i : i+2] == "BA" :
        flag_ba = True
if flag_ba and flag_ab :
    print("YES") 
else : 
    print("NO")  