#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 7;
int n, q, root;
vector<int> g[N];
int par[N], f[N], cnt_leaves, is_leaf[N], sz[N], heavy_son[N];
void dfs(int u, int p = 0) {
par[u] = p;
f[u] = 0;
sz[u] = 1;
for (auto v : g[u]) {
if (v != p) {
dfs(v, u);
f[u] += f[v];
sz[u] += sz[v];
if (sz[v] > sz[heavy_son[u]]) {
heavy_son[u] = v;
}
}
}
if (g[u].size() == 1) is_leaf[u] = 1, f[u]++, cnt_leaves++;
}
int l[N], tt = 0, head[N], ord[N], pref[2][N];
void dfs_heavy(int u, int p) {
l[u] = ++tt;
ord[tt] = u;
head[u] = p;
if (heavy_son[u]) {
dfs_heavy(heavy_son[u], p);
}
for (auto v : g[u]) {
if (v != par[u] && v != heavy_son[u]) {
dfs_heavy(v, v);
}
}
}
vector<int> events;
void update(int u) {
while (u != 0) {
events.push_back(l[head[u]]);
events.push_back(l[u] + 1);
u = par[head[u]];
}
}
int get_sum(int s, int l, int r) {
if (l > r) return 0;
return pref[s][r] - pref[s][l - 1];
}
int get() {
sort(events.begin(), events.end());
//events.resize(unique(events.begin(), events.end()) - events.begin());
events.push_back(n + 1);
int ans = 0;
ans += get_sum(0, 1, events[0] - 1);
for (int i = 0; i + 1 < events.size(); ++i) {
ans += get_sum((i + 1) & 1, events[i], events[i + 1] - 1);
}
return ans;
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> q;
for (int i = 1; i < n; ++i) {
int a, b;
cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i = 1; i <= n; ++i) if (g[i].size() >= 2) root = i;
dfs(root);
dfs_heavy(root, root);
for (int i = 1; i <= n; ++i) f[i] %= 2;
for (int b = 0; b < 2; ++b) {
for (int i = 1; i <= n; ++i) {
pref[b][i] = pref[b][i - 1] + ((f[ord[i]] ^ b) == 0);
}
}
int id = 0;
while (q--) {
int m;
cin >> m;
events.clear();
int here = cnt_leaves;
vector<int> changes;
for (int i = 0; i < m; ++i) {
int a;
cin >> a;
f[a] ^= 1;
here++;
if (is_leaf[a] == 1) {
update(a);
here--;
changes.push_back(a);
}
update(a);
is_leaf[a] = 0;
}
if (here % 2 == 0) {
cout << n + m + get() - 2 << "\n";
} else {
cout << -1 << "\n";
}
for (auto x : changes) is_leaf[x] = 1;
}
return 0;
}
