#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 100'000 + 10;
const int MAX_LG = 17;
int n, q, r, st[MAX_N], ft[MAX_N], h[MAX_N], par[MAX_N][MAX_LG], odds[MAX_N][MAX_LG], base;
vector<int> adj[MAX_N];
int vpar[MAX_N];
vector<int> vadj[MAX_N];
bool dp[MAX_N];
void dfs(int u, int p) {
static int time = 0;
st[u] = time++;
if (adj[u].size() == 1) {
odds[u][0] = 1;
}
for (int v : adj[u]) {
if (v != p) {
h[v] = h[u] + 1;
par[v][0] = u;
dfs(v, u);
odds[u][0] ^= odds[v][0];
}
}
if (u != r && odds[u][0] == 0) {
++base;
}
ft[u] = time;
}
int get_lca(int u, int v) {
if (h[u] < h[v]) swap(u, v);
for (int i = 0, diff = h[u] - h[v]; diff != 0; ++i, diff >>= 1) {
if (diff & 1) u = par[u][i];
}
if (u == v) return u;
for (int i = MAX_LG - 1; i >= 0; --i) {
if (par[u][i] != par[v][i]) {
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
int get_odds(int u, int k) {
int res = 0;
for (int i = 0; k != 0; ++i, k >>= 1) {
if (k & 1) {
res += odds[u][i];
u = par[u][i];
}
}
return res;
}
void vdfs(int u) {
for (int v : vadj[u]) {
vdfs(v);
dp[u] ^= dp[v];
}
}
int main() {
cin >> n >> q;
for (int e = 1; e <= n - 1; ++e) {
int u, v;
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
r = 1;
while (adj[r].size() == 1) ++r;
dfs(r, -1);
for (int i = 1; i < MAX_LG; ++i) {
for (int u = 1; u <= n; ++u) {
par[u][i] = par[par[u][i - 1]][i - 1];
odds[u][i] = odds[u][i - 1] + odds[par[u][i - 1]][i - 1];
}
}
while (q--) {
int d;
cin >> d;
vector<int> V = {r};
for (int i = 0; i < d; ++i) {
int v;
cin >> v;
dp[v] ^= 1;
V.push_back(v);
}
static auto cmp = [&] (int u, int v) { return st[u] < st[v]; };
sort(V.begin(), V.end(), cmp);
V.erase(unique(V.begin(), V.end()), V.end());
for (int i = int(V.size()) - 2; i >= 0; --i) {
V.push_back(get_lca(V[i], V[i + 1]));
}
sort(V.begin(), V.end(), cmp);
V.erase(unique(V.begin(), V.end()), V.end());
for (int i = 1; i < V.size(); ++i) {
vpar[V[i]] = V[i - 1];
while (ft[vpar[V[i]]] < ft[V[i]]) {
vpar[V[i]] = vpar[vpar[V[i]]];
}
vadj[vpar[V[i]]].push_back(V[i]);
if (adj[V[i]].size() == 1) {
dp[V[i]] ^= 1;
}
}
vdfs(r);
if (odds[r][0] ^ dp[r]) {
cout << -1 << '\n';
} else {
int res = n + d - 1 + base;
for (int v : V) {
if (v == r || !dp[v]) continue;
res += 2 * get_odds(v, h[v] - h[vpar[v]]) - (h[v] - h[vpar[v]]);
}
cout << res << '\n';
}
for (int v : V) {
vpar[v] = 0;
vadj[v].clear();
dp[v] = 0;
}
}
}
