import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    def win(l,r):
        if (l,r) in dp:return dp[l,r]
        if l+1==r:return False
        if l==r:return True
        res=False
        for nl in range(l+1,min(r,lto[l])):
            if not win(nl,r):
                res=True
                break
        for nr in range(r-1,max(l,rto[r]),-1):
            if res:break
            if win(l,nr)==0:
                res=1
                break
        dp[l,r]=res
        return res

    n,x=MI()
    aa=LI()

    lto=[-1]*n
    r=-1
    s=0
    for l in range(n):
        while r<n and s<=x:
            r+=1
            if r>=n:break
            s+=aa[r]
        lto[l]=r
        s-=aa[l]

    rto=[-1]*(n+1)
    l=n
    s=0
    for r in range(n,-1,-1):
        while l>=0 and s<=x:
            l-=1
            if l<0:break
            s+=aa[l]
        rto[r]=l
        s-=aa[r-1]

    dp={}
    if win(0,n):print("A")
    else:print("B")

main()