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.

def main():
	a=input()
	try:
		i=a.index("AB")
		j=a.index("BA")
	except:
		print("NO")
		return
	if abs(i-j)>1:
		print("YES")
	else:
		print("NO")
		
main()