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 check(s):
    n=len(s)
    c1,c2=0,0
    index=0
    while True:
        if(s[index]=='A' and s[index+1]=='B'):
            c1+=1
            index+=2
            if(index>=n):break
        elif(s[index]=='B' and s[index+1]=='A'):
            c2+=1
            index+=2
            if(index>=n):break
    if(c1>0 and c2>0):return True
    return False
    
s=input()
if(check(s)):print('YES')
else:print('NO')