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.
s = str(input())
a = 0
b = 0
i = 0
ans = []
while i < (len(s)-1) :
    if s[i] == "A" and s[i+1] == "B" :
        a += 1
        ans.append(i)

        i += 1
    elif s[i] == "B" and s[i+1] == "A" :
        b += 1
        ans.append(i)
        i += 2
    else:
        i += 1
if a>=2 and b>=2 :
    print("YES")
elif a<1 or b<1:
    print("NO")
else:
    diff =[]
    for i in range(len(ans)-1):
        diff.append(ans[i+1] - ans[i])
    aaa = False
    for i in range(len(diff)):
        if diff[i] > 1:
            aaa = True

    if aaa:
        print("YES")
    else:
        print("NO")