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.

if __name__=='__main__':
    s_arr = input()
    n_arr = []
    for i in s_arr:
        n_arr.append(i)
    # print(s_arr, n_arr)
    ab = 0
    ba = 0
    for i in range(len(n_arr)-1):
        c = n_arr[i]
        # print(c)
        if c == 'A' and n_arr[i+1] == 'B':
            # print("ab case")
            ab=1
            n_arr[i]='x'
            n_arr[i+1]='x'
        elif c == 'B' and n_arr[i+1] == 'A':
            # print("ba case")
            ba=1
            n_arr[i]='x'
            n_arr[i+1]='x'
        n_arr.append(c)
        
    if ab == 1 and ba == 1:
        print("YES")
    else:
        print("NO")