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.
from sys import stdin; inp = stdin.readline
from math import dist, ceil, floor, sqrt, log
def IA(): return list(map(int, inp().split()))
def FA(): return list(map(float, inp().split()))
def SA(): return inp().split()
def I(): return int(inp())
def F(): return float(inp())
def S(): return inp()

def main():
    s=S()
    x = s.find('AB')
    y = s.find('BA')
    if (x == y ==-1) or (y==x+1):
        return 'NO'
    return 'YES'

if __name__ == '__main__':
    print(main())