#include <bits/stdc++.h>
using namespace std;
const int INFINI = 1e9;
vector<vector<int>> graphe;
int N, Q;
int solve() {
vector<int> parent(N);
vector<int> nbEnfants(N, 0);
vector<int> feuilles;
// cerr << "done";
// Trouver la racine
vector<int> distances(N, INFINI);
queue<int> bfs;
for (int iNoeud = 0; iNoeud < N; iNoeud++) {
if (graphe[iNoeud].size() == 1) {
bfs.push(iNoeud);
nbEnfants[iNoeud] = 0;
feuilles.push_back(iNoeud);
}
}
// cerr << feuilles.size();
if (feuilles.size() % 2 == 1) return -1;
// cerr << "done";
int distance = 0;
while (!bfs.empty()) {
int taille = bfs.size();
for (int i = 0; i < taille; i++) {
int noeud = bfs.front();
bfs.pop();
if (distances[noeud] != INFINI) continue;
distances[noeud] = distance;
for (int iVoisin : graphe[noeud]) {
if (distances[iVoisin] != INFINI) bfs.push(iVoisin);
}
}
distance++;
}
int distMax = -1, noeudMax = -1;
for (int i = 0; i < N; i++) {
if (distances[i] > distMax) {
distMax = distances[i];
noeudMax = i;
}
}
// cerr << "done";
parent[noeudMax] = -1;
// L'enraciner
bfs.push(noeudMax);
vector<bool> visited(N);
while (!bfs.empty()) {
int noeud = bfs.front();
bfs.pop();
if (visited[noeud]) continue;
visited[noeud] = true;
for (int iVoisin : graphe[noeud]) {
if (!visited[iVoisin]) {
parent[iVoisin] = noeud;
nbEnfants[noeud]++;
bfs.push(iVoisin);
}
}
}
// cerr << "done";
vector<pair<int, int>> storage(N, {0, 0});
for (int i : feuilles) {
bfs.push(i);
storage[i].first++;
}
int res = 0;
while (!bfs.empty()) {
int noeud = bfs.front();
bfs.pop();
if (parent[noeud] == -1) {
break;
}
while (storage[noeud].first > 2) {
storage[noeud].first -= 2;
}
while (storage[noeud].second > 0 && (storage[noeud].first > 0 || storage[noeud].second > 1)) {
storage[noeud].second--;
}
storage[parent[noeud]].first += storage[noeud].first;
storage[parent[noeud]].second += storage[noeud].second;
res += storage[noeud].first;
res += storage[noeud].second*2;
nbEnfants[parent[noeud]]--;
if (nbEnfants[parent[noeud]] == 0) bfs.push(parent[noeud]);
}
return res;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> N >> Q;
graphe.resize(2*N+2);
for (int i = 0; i < N-1; i++) {
int u, v;
cin >> u >> v;
u--; v--;
graphe[u].push_back(v);
graphe[v].push_back(u);
}
for (int i = 0; i < Q; i++) {
int nbFeuilles;
cin >> nbFeuilles;
vector<int> feuilles(nbFeuilles);
for (int& i2 : feuilles) cin >> i2;
for (int i2 = 0; i2 < nbFeuilles; i2++) {
graphe[feuilles[i2]-1].push_back(N+i2);
graphe[N+i2].push_back(feuilles[i2]-1);
}
N += nbFeuilles;
cerr << solve() << '\n';
N -= nbFeuilles;
for (int i2 = 0; i2 < nbFeuilles; i2++) {
graphe[feuilles[i2]-1].pop_back();
graphe[N+i2].pop_back();
}
}
}
