Problem: We have a tree with N vertices numbered 1 to N. The i-th edge in this tree connects Vertex a_i and Vertex b_i.
Consider painting each of these edges white or black. There are 2^{N-1} such ways to paint the edges. Among them, how many satisfy all of the following M restrictions?

* The i-th (1 \leq i \leq M) restriction is represented by two integers u_i and v_i, which mean that the path connecting Vertex u_i and Vertex v_i must contain at least one edge painted black.

Constraints

* 2 \leq N \leq 50
* 1 \leq a_i,b_i \leq N
* The graph given in input is a tree.
* 1 \leq M \leq \min(20,\frac{N(N-1)}{2})
* 1 \leq u_i < v_i \leq N
* If i \not= j, either u_i \not=u_j or v_i\not=v_j
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N
a_1 b_1
:
a_{N-1} b_{N-1}
M
u_1 v_1
:
u_M v_M


Output

Print the number of ways to paint the edges that satisfy all of the M conditions.

Examples

Input

3
1 2
2 3
1
1 3


Output

3


Input

2
1 2
1
1 2


Output

1


Input

5
1 2
3 2
3 4
5 3
3
1 3
2 4
2 5


Output

9


Input

8
1 2
2 3
4 3
2 5
6 3
6 7
8 6
5
2 7
3 5
1 6
2 8
7 8


Output

62

Solution (in PYTHON3):

Solution:
def main():
    from itertools import combinations
    n = int(input())
    ab = [tuple(sorted(list(map(int, input().split())))) for _ in [0]*(n-1)]
    m = int(input())
    uv = [list(map(int, input().split())) for _ in [0]*m]
    g = [[] for _ in [0]*n]
    [g[a-1].append(b-1) for a, b in ab]
    [g[b-1].append(a-1) for a, b in ab]

    d = dict()
    for i, (a, b) in enumerate(ab):
        d[(a-1, b-1)] = i

    def tree_path(root, goal):
        d = [-1]*n  # 根からの距離
        d[root] = 0
        q = [root]
        cnt = 0
        while q:  # BFS
            cnt += 1
            qq = []
            while q:
                i = q.pop()
                for j in g[i]:
                    if d[j] == -1:
                        d[j] = cnt
                        qq.append(j)
            q = qq
        now = goal
        path = [goal]
        while True:
            dist = d[now]
            for i in g[now]:
                if d[i] < dist:
                    now = i
                    path.append(i)
                    break
            if dist == 1:
                break
        return path

    seiyaku = [set() for _ in [0]*m]

    for i, (u, v) in enumerate(uv):
        path = tree_path(u-1, v-1)
        for j in range(len(path)-1):
            x, y = min(path[j], path[j+1]), max(path[j], path[j+1])
            seiyaku[i].add(d[(x, y)])

    cnt = 2**(n-1)

    for i in range(1, m+1):
        flag = 1
        if i % 2 == 1:
            flag = -1
        cc = combinations(list(range(m)), i)
        for c in cc:
            s = set()
            for j in c:
                s |= seiyaku[j]
            cnt += (2**(n-1-len(s)))*flag
    print(cnt)


main()