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.
string = input()
countA= string.count('A')
countB = string.count('B')

if (countA + countB)%2:
    print("NO")
else:
    firstA= string.find('A')
    firstB= string.find('B')
    if abs(firstA - firstB) != 1:
        print("NO")
    else:
        secondA= string.find('A', firstA+1)
        secondB= string.find('B', firstB+1)
        if abs(secondA - secondB) != 1:
            print("NO")
        else:
            print("YES")
    
        
