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.
import sys
input=sys.stdin.readline
a=input()
ab=False
ba=False
i=0
while i+1<len(a):
	if ab and ba:
		break
	if a[i]=="A" and a[i+1]=="B":
		i+=2
		ab=True
	elif a[i]=="B" and a[i+1]=="A":
		i+=1
		ba=True
	else:
		i+=1
if ab and ba:
	print("YES")
else:
	print("NO")