from collections import defaultdict
n, m = map(int, input().split(" "))
arr = [int(i) for i in input().split(" ")]
d = defaultdict(list)
for i in range(n - 1):
    x, y = map(int, input().split(" "))
    d[x].append(y)
    d[y].append(x)
cnt = 0
def slv(a, k, pr):
    global cnt
    if k > m:
        return
    ok = 1
    for i in range(len(d[a])):
        if d[a][i] != pr:
            ok = 0
            slv(d[a][i], (k + 1)* arr[d[a][i] - 1], a)
    cnt += ok
slv(1, arr[0], -1)
print(cnt)