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.
a=input()
flag=False

for c in range(0,len(a)):
    if a[c:c+2]=="AB":
        try:
            if a[c+2:len(a)].count("BA")!=0:flag=True
        except:
            flag=False
    if a[c:c+2]=="BA":
        try:
            if a[c+2:len(a)].count("AB")!=0:flag=True
        except:
            flag=False
if flag:print("YES")
else:print("NO")