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()
n=len(s)
ab=0
ba=0
aba=0
for i in range(n-1):
	if s[i]=="A" and s[i+1]=="B":
		ab+=1
		if i<n-2 and s[i+2]=="A":
			aba+=1
	elif s[i]=="B" and s[i+1]=="A":
		ba+=1
if aba>0 and (ab==1 or ba==1):
	print("NO")
else:
	print("YES")