A tree is a connected graph that doesn't contain any cycles.

The distance between two vertices of a tree is the length (in edges) of the shortest path between these vertices.

You are given a tree with *n* vertices and a positive number *k*. Find the number of distinct pairs of the vertices which have a distance of exactly *k* between them. Note that pairs (*v*, *u*) and (*u*, *v*) are considered to be the same pair.
The first line contains two integers *n* and *k* (1 ≤ *n* ≤ 50000, 1 ≤ *k* ≤ 500) — the number of vertices and the required distance between the vertices.

Next *n* - 1 lines describe the edges as "*a*<sub class="lower-index">*i*</sub> *b*<sub class="lower-index">*i*</sub>" (without the quotes) (1 ≤ *a*<sub class="lower-index">*i*</sub>, *b*<sub class="lower-index">*i*</sub> ≤ *n*, *a*<sub class="lower-index">*i*</sub> ≠ *b*<sub class="lower-index">*i*</sub>), where *a*<sub class="lower-index">*i*</sub> and *b*<sub class="lower-index">*i*</sub> are the vertices connected by the *i*-th edge. All given edges are different.
5 2
1 2
2 3
3 4
2 5
4
5 3
1 2
2 3
3 4
4 5
2
10 1
2 1
3 1
4 3
5 4
6 5
7 1
8 6
9 2
10 6
9
10 2
2 1
3 1
4 3
5 4
6 5
7 1
8 6
9 2
10 6
10
10 3
2 1
3 1
4 3
5 4
6 5
7 1
8 6
9 2
10 6
8
50 3
2 1
3 2
4 3
5 4
6 5
7 6
8 7
9 8
10 9
11 10
12 11
13 12
14 13
15 14
16 15
17 16
18 17
19 18
20 19
21 20
22 21
23 22
24 23
25 24
26 25
27 26
28 27
29 28
30 29
31 30
32 31
33 32
34 33
35 34
36 35
37 36
38 37
39 38
40 39
41 40
42 41
43 42
44 43
45 44
46 45
47 46
48 47
49 48
50 49
47
50 4
2 1
3 1
4 2
5 2
6 3
7 3
8 4
9 4
10 5
11 5
12 6
13 6
14 7
15 7
16 8
17 8
18 9
19 9
20 10
21 10
22 11
23 11
24 12
25 12
26 13
27 13
28 14
29 14
30 15
31 15
32 16
33 16
34 17
35 17
36 18
37 18
38 19
39 19
40 20
41 20
42 21
43 21
44 22
45 22
46 23
47 23
48 24
49 24
50 25
124
50 5
2 1
3 1
4 2
5 2
6 4
7 4
8 6
9 6
10 8
11 8
12 10
13 10
14 12
15 12
16 14
17 14
18 16
19 16
20 18
21 18
22 20
23 20
24 22
25 22
26 24
27 24
28 26
29 26
30 28
31 28
32 30
33 30
34 32
35 32
36 34
37 34
38 36
39 36
40 38
41 38
42 40
43 40
44 42
45 42
46 44
47 44
48 46
49 46
50 48
84
10 20
2 1
3 2
4 1
5 3
6 4
7 1
8 2
9 7
10 2
0
def dfs(node, parent, graph, depth, k, cnt):
    global result

    depth[node] = depth[parent] + 1 if parent is not None else 0

    if depth[node] == k:
        result += 1

    for neighbor in graph[node]:
        if neighbor != parent:
            dfs(neighbor, node, graph, depth, k, cnt)

    cnt[node] = 1
    for neighbor in graph[node]:
        if neighbor != parent:
            cnt[node] += cnt[neighbor]

    if depth[node] >= k:
        result += cnt[node] - cnt[parent]

def solve(graph, n, k):
    global result
    depth = [0] * n
    cnt = [0] * n
    dfs(0, None, graph, depth, k, cnt)

n, k = map(int, input().split())
graph = [[] for _ in range(n)]
for _ in range(n - 1):
    u, v = map(int, input().split())
    graph[u - 1].append(v - 1)
    graph[v - 1].append(u - 1)
result = 0
solve(graph, n, k)
print(result)
