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 solve():
	s = input()
	
	l = 0
	r = len(s) - 1
	is_AB = True

	for i in range(r):
		d = s[i:i+2]
		if d == 'AB':
			break
		elif d == 'BA':
			is_AB = False
			break

	while r > l+2:
		d = s[r-1:r+1]
		
		if (is_AB and d == 'BA') or (is_AB is False and d == 'AB'):
			print("YES")
			break

		r -= 1
	else:
		print("NO")	

if __name__ == "__main__":
	solve()