n, x = [int(w) for w in input().split()]
a = [int(w) for w in input().split()]
def f(i, j):
    return (0, 0) if i>x and j>x else (i, j)
l = [(0, 0, i, i) for i in a]
while len(l) > 1:
    l = [f(t[0]+u[3], u[1]+t[2])+  (t[2], u[3])
         for t, u in zip(l, l[1:])]
print("A" if l[0][0] else "B")