#include <bits/stdc++.h>
using namespace std;
#define sz(x) ((int)size(x))
#define all(x) begin(x), end(x)
#define trace(x) cout << #x << ": " << (x) << endl;
typedef long long ll;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r) { return (int) ((ll) rnd() % (r - l + 1)) + l; }
const int N = 100000, infI = 1e9 + 7;
const ll infL = 3e18;
vector<int> g[N * 2];
ll dp[3][N]; //LL???
void dfs(int v, int p) {
dp[0][v] = 0;
dp[1][v] = dp[2][v] = infL;
if (sz(g[v]) <= 1) {
//v is a leaf
dp[1][v] = 1;
} else {
for (int to: g[v]) {
if (to != p) {
dfs(to, v);
array<ll, 3> dq = {dp[0][v], dp[1][v], dp[2][v]};
dp[0][v] = min({dq[2] + dp[2][to], dq[1] + dp[1][to]});
dp[1][v] = min({dq[0] + dp[1][to], dq[2] + dp[1][to], dq[1] + dp[2][to]});
dp[2][v] = min({dq[0] + dp[2][to], dq[2] + dp[2][to], dq[1] + dp[1][to]});
}
}
dp[1][v] += 1;
dp[2][v] += 2;
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, q;
cin >> n >> q;
int root = -1;
for (int i = 0; i < n - 1; ++i) {
int a, b;
cin >> a >> b;
--a, --b;
g[a].push_back(b);
g[b].push_back(a);
}
for (int i = 0; i < n; ++i) {
if (sz(g[i]) > 1) {
root = i;
break;
}
}
assert(root != -1);
while (q--) {
int D;
cin >> D;
vector<int> a(D);
for (int i = 0; i < D; ++i) {
cin >> a[i];
--a[i];
g[a[i]].push_back(i + n);
}
dfs(root, -1);
cout << (dp[0][root] >= infL ? -1 : dp[0][root]) << '\n';
for (int i = 0; i < D; ++i) {
g[a[i]].pop_back();
}
}
return 0;
}
