#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 2e5 + 5;
int old_n, q;
int n;
vector<int> adj[MAX_N];
int n_added[MAX_N];
int n_ls[MAX_N];
int ans;
void dfs(int u, int par) {
n_ls[u] = (adj[u].size() == 1) ? 1 : 0;
for (int v : adj[u]) {
if (v == par) continue;
dfs(v, u);
n_ls[u] += n_ls[v];
}
n_ls[u] %= 2;
if (par != -1 && n_ls[u] == 0) n_ls[u] = 2;
ans += n_ls[u];
}
void init() {
ans = 0;
}
void do_query(int query) {
int d_n; cin >> d_n;
n = old_n + d_n;
init();
for (int u = old_n + 1; u <= n; u++) {
int v; cin >> v;
adj[u].push_back(v);
adj[v].push_back(u);
n_added[u]++;
n_added[v]++;
}
for (int u = 1; u <= n; u++) {
if (adj[u].size() == 1) continue;
dfs(u, -1);
if (n_ls[u]) cout << "-1" << '\n';
else cout << ans << '\n';
for (int v = 1; v <= n; v++) {
while (n_added[v]) {
adj[v].pop_back();
n_added[v]--;
}
}
return;
}
}
int main() {
// freopen("spring.in", "r", stdin);
cin.sync_with_stdio(false);
cin.tie(0);
cin >> old_n >> q;
for (int i = 1; i < old_n; i++) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= q; i++) do_query(i);
}
