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.
s=input()
s=s.capitalize()
l=[]
i=0
while i<len(s):
    if s[i:i+2] == "AB" and "BA" in l:
        print("YES")
        exit()
    if s[i:i+2] == "BA" and "AB" in l:
        print("YES")
        exit()
    elif s[i:i+2] == "BA" and "BA" not in l:
        l.append(s[i:i+2])
    elif s[i:i+2] == "AB" and "AB" not in l:
        l.append(s[i:i+2])
    i+=2
if i!=len(l):
    if s[i:] == "AB" and "BA" in l:
        print("YES")
        exit()
    if s[i:] == "BA" and "AB" in l:
        print("YES")
        exit()
if len(l)<2:
    print("NO")
  		   								   				 	 	 				