/// @author Camillus
#include <bits/stdc++.h>
using namespace std;

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n, q;
    cin >> n >> q;

    vector<pair<int, int>> edges(n - 1);
    for (auto &[u, v] : edges) {
        cin >> u >> v;
    }

    auto result = [&edges]() -> int {
        int n = (int)edges.size() + 1;

        vector<vector<int>> g(n);
        for (auto [u, v] : edges) {
            u--;
            v--;
            g[u].push_back(v);
            g[v].push_back(u);
        }

        int answer = 0;

        auto dfs = [&](auto &&self, int u, int p) -> int {
            if (g[u].size() == 1) {
                return 1;
            }

            int sum = 0;

            for (int v : g[u]) {
                if (v == p) {
                    continue;
                }

                int current = self(self, v, u);

                if (current % 2 == 1) {
                    answer += 1;
                } else {
                    answer += 2;
                }

                sum += current;
            }

            return sum;
        };

        int root = 0;
        for (int u = 0; u < n; u++) {
            if (g[u].size() > 1) {
                root = u;
            }
        }

        int current = dfs(dfs, root, -1);

        if (current % 2 == 1) {
            return -1;
        } else {
            return answer;
        }
    };

    for (int i = 0; i < q; i++) {
        edges.resize(n - 1);

        int d;
        cin >> d;

        for (int u = 1; u <= d; u++) {
            int v;
            cin >> v;

            edges.emplace_back(u + n, v);
        }
        cout << result() << '\n';
    }
    return 0;
}