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():
	s = input()

	ab = []
	ba = []
	for i in range(len(s)-1):
		if s[i:i+2]=="AB":
			if any(abs(x-i)>1 for x in ba):
				print("YES")
				return
			ab.append(i)
		elif s[i:i+2]=="BA":
			if any(abs(x-i)>1 for x in ab):
				print("YES")
				return
			ba.append(i)
	print("NO")
main()
