#pragma GCC optimize("O2,unroll-loops,Ofast")
#include <bits/stdc++.h>
using namespace std;
const int N = 200'000;
int n, q, d, deg[N + 10];
int sz[N + 10], ans;
vector<int> adj[N + 10];
void readInput() {
cin >> n >> q;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; i++)
deg[i] = adj[i].size();
}
void dfs(int u = 1, int par = 0) {
sz[u] = (adj[u].size() == 1);
for (auto v: adj[u])
if (v != par) {
dfs(v, u);
sz[u] += sz[v];
}
if (par)
ans += 1 + (sz[u] % 2 == 0);
}
void query() {
cin >> d;
for (int i = 1; i <= d; i++) {
int u = n + i, v;
cin >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
int all = 0;
for (int i = 1; i <= n + d; i++)
if (adj[i].size() == 1)
all++;
if (all % 2)
cout << -1 << '\n';
else {
ans = 0;
dfs();
cout << ans << '\n';
}
for (int i = 1; i <= n; i++)
while (deg[i] != adj[i].size()) {
int v = adj[i].back();
adj[i].pop_back();
adj[v].pop_back();
}
}
void solveSub4() {
while (q--)
query();
cout.flush();
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
readInput();
solveSub4();
return 0;
}
