#include <bits/stdc++.h>
#define int long long
#define MULTITEST false
using namespace std;
const int INF = 1e18;
vector<int> vp;
vector<vector<int>> roads;
pair<int, int> compute (int node, int parent) {
vector<int> dp1, dp2;
int oblig = 0;
int oblig_cnt = 0;
for (int next : roads[node]) if (next != parent) {
pair<int, int> sub = compute(next, node);
if (sub.first == INF) {
oblig += sub.second;
oblig_cnt += 2;
} else if (sub.second == INF) {
oblig += sub.first;
oblig_cnt ++;
} else {
dp1.push_back(sub.first);
dp2.push_back(sub.second);
}
}
for (int i = 0; i < vp[node]; i ++) {
oblig ++;
oblig_cnt ++;
}
if (dp1.size() + oblig_cnt == 0) {
return { 1, INF };
}
vp[node] = 0;
int mvr = 0;
for (int u : dp1) mvr = u;
int mpr = INF;
for (int i = 0; i < dp1.size(); i ++)
mpr = min(mpr, dp2[i] - dp1[i]);
int np1 = mvr + oblig;
int np2 = mvr + mpr + oblig;
if (((dp1.size() + oblig_cnt) & 1) == 0) swap(np1, np2);
np1 ++;
np2 += 2;
if (np1 >= INF) np1 = INF;
if (np2 >= INF) np2 = INF;
assert(np1 == INF || np2 == INF);
return { np1, np2 };
}
void solve () {
int N, Q; cin >> N >> Q;
vp.resize(N);
roads.resize(N);
vector<int> deg(N);
for (int i = 1; i < N; i ++) {
int a, b;
cin >> a >> b;
a --; b --;
roads[a].push_back(b);
roads[b].push_back(a);
deg[a] ++; deg[b] ++;
}
int root = 0;
for (; root < N; root ++)
if (deg[root] != 1)
break ;
for (int i = 0; i < Q; i ++) {
int d;
cin >> d;
for (int j = 0; j < d; j ++) {
int x;
cin >> x;
x --;
vp[x] ++;
}
pair<int, int> U = compute(root, -1);
int res = U.second;
if (res >= INF) cout << -1 << "\n";
else cout << (res - 2) << "\n";
}
}
signed main () {
ios_base::sync_with_stdio(false); cin.tie(NULL);
int T = 1;
if (MULTITEST) cin >> T;
for (int t = 0; t < T; t ++) solve();
}
