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.
# import sys, os
# sys.stdin = open(os.path.join(sys.path[0], "input.txt"), "r")
# sys.stdout = open(os.path.join(sys.path[0], "output.txt"), "w")

string = input()
org, rev = False, False
for i in range(0, len(string) - 1):
    if(string[i] + string[i + 1] == 'AB'):
        if(i == 0 or string[i - 1] != 'B'):
            org = True
        else:
            break;
    elif(string[i] + string[i + 1] == 'BA'):
        if(i == 0 or string[i - 1] != 'A'):
            rev = True
        else:
            break;

print("YES" if(org and rev) else "NO")






        







    


