#include <bits/stdc++.h>
using namespace std;
int n, q;
vector<int> graph[100001];
int leaves[100001], tot_leaves = 0, bad = 0;
bool is_leaf[100001];
int tin[100001], tout[100001], timer = 0, anc[100001][18];
vector<int> vtree[100001];
int ans, bit[100001];
int a[100001], l_delta[100001];
void update(int pos, int val) { for (; pos <= n; pos += pos & -pos) bit[pos] += val; }
int query(int l, int r) {
int res = 0;
for (; r; r -= r & -r) res += bit[r];
for (l--; l; l -= l & -l) res -= bit[l];
return res;
}
void lca_dfs(int node, int parent = 0) {
// LCA stuff
tin[node] = ++timer;
for (int i = 1; i < 18; i++) anc[node][i] = anc[anc[node][i - 1]][i - 1];
// Check whether it's a leaf
if (graph[node].size() == 1) {
leaves[node] = 1;
tot_leaves++;
is_leaf[node] = true;
}
// DFS on children
for (int i : graph[node]) if (i != parent) {
anc[i][0] = node;
lca_dfs(i, node);
leaves[node] += leaves[i];
}
tout[node] = timer;
// Set what happens when we toggle the parity
if (leaves[node] & 1) update(tin[node], 1), update(tout[node] + 1, -1);
else {
update(tin[node], -1), update(tout[node] + 1, 1);
bad++;
}
}
bool is_ancestor(int u, int v) { return tin[u] <= tin[v] && tout[u] >= tout[v]; }
int lca(int u, int v) {
if (is_ancestor(u, v)) return u;
for (int i = 17; ~i; i--) if (anc[u][i] && !is_ancestor(anc[u][i], v)) u = anc[u][i];
return anc[u][0];
}
void vtree_dfs(int node, int parent = 0) {
for (int i : vtree[node]) if (i != parent) {
vtree_dfs(i, node);
l_delta[node] += l_delta[i];
}
ans += (l_delta[node] & 1) * query(tin[parent] + 1, tin[node]);
}
bool cmp(int u, int v) { return tin[u] < tin[v]; }
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> q;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
graph[u].push_back(v);
graph[v].push_back(u);
}
for (int i = 1; i <= n; i++) if (graph[i].size() > 1) {
lca_dfs(i);
break;
}
while (q--) {
// Read query data and update original tree
int d;
cin >> d;
vector<int> nodes;
for (int i = 0; i < d; i++) {
cin >> a[i];
if (is_leaf[a[i]]) is_leaf[a[i]] = false;
else {
leaves[a[i]]++;
tot_leaves++;
l_delta[a[i]]++;
nodes.push_back(a[i]);
}
}
// Construct the virtual tree
sort(nodes.begin(), nodes.end(), cmp);
int m = nodes.size();
for (int i = 1; i < m; i++) nodes.push_back(lca(nodes[i - 1], nodes[i]));
sort(nodes.begin(), nodes.end(), cmp);
nodes.erase(unique(nodes.begin(), nodes.end()), nodes.end());
vector<int> stck;
for (int i : nodes) {
while (stck.size() > 1 && !is_ancestor(stck.back(), i)) {
vtree[stck[stck.size() - 2]].push_back(stck.back());
stck.pop_back();
}
stck.push_back(i);
}
while (stck.size() > 1) {
vtree[stck[stck.size() - 2]].push_back(stck.back());
stck.pop_back();
}
// Compute and output the answer
if (tot_leaves & 1) cout << "-1\n";
else {
ans = n + d + bad - 2;
if (stck.size()) vtree_dfs(stck[0]);
cout << ans << '\n';
}
// Reset the original tree
for (int i = 0; i < d; i++) {
if (leaves[a[i]] == 1) is_leaf[a[i]] = true;
else {
leaves[a[i]]--;
tot_leaves--;
}
}
// Reset the vtree
for (int i : nodes) {
vtree[i].clear();
l_delta[i] = 0;
}
}
return 0;
}
