#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
// #include <ext/pb_ds/tree_policy.hpp>
using namespace std;
// using namespace __gnu_pbds;
#define int long long
#define mod 1000000007
#define base 7001
#define base2 757
#define F first
#define S second
// #define pi acos(-1)
#define double long double
// #define ordered_set tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update>
// #define ordered_multiset tree<int, null_type, less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
// #pragma GCC optimize("O3,Ofast,unroll-loops")
// #pragma GCC target("avx2,sse3,sse4,avx")
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
constexpr int maxn = 400001;
const int N = 1 << (int)(ceil(log2(maxn)));
int n, q, d[maxn], in[maxn], jump[18][maxn], parity[maxn], prf[maxn], tim, ans;
vector<int> adj[maxn], vrt[maxn];
bool vis[maxn];
int dfs(int v) {
in[v] = tim++, vis[v] = 1;
int num = 0;
if (adj[v].size() == 1) num = 1;
for (int u : adj[v]) {
if (!vis[u]) {
jump[0][u] = v;
d[u] = d[v] + 1;
int x = dfs(u);
ans += x;
num += x;
}
}
parity[v] = (num % 2 ? 1 : -1);
return 2 - num % 2;
}
void calc(int v, int cur) {
vis[v] = 1, prf[v] = cur;
for (int u : adj[v]) if (!vis[u]) calc(u, cur + parity[u]);
}
int rt = 1;
void build() {
jump[0][rt] = rt;
for (int i = 1; i < 18; i++) {
for (int j = 1; j <= n; j++) jump[i][j] = jump[i - 1][jump[i - 1][j]];
}
}
int lca(int v, int u) {
if (v == u) return v;
if (d[v] > d[u]) swap(u, v);
int t = d[u] - d[v];
for (int k = 17; k >= 0; k--) {
if (((1 << k) & t)) u = jump[k][u];
}
for (int k = 17; k >= 0; k--) {
if (jump[k][v] != jump[k][u]) v = jump[k][v], u = jump[k][u];
}
return jump[0][v];
}
int cnt;
int answer(int v) {
int num = 0;
for (int u : vrt[v]) {
int x = dfs(u);
if (x % 2) cnt += prf[u] - prf[v];
num += x;
}
return num % 2;
}
signed main()
{
cin.tie(0) -> sync_with_stdio(0);
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);
if (adj[v].size() > 1) rt = v;
}
int cccc = 0;
for (int i = 1; i <= n; i++) {
if (adj[i].size() == 1) cccc++;
}
dfs(rt);
memset(vis, 0, sizeof vis);
calc(rt, 0);
memset(vis, 0, sizeof vis);
build();
while (q--) {
int t; cin >> t;
vector<pair<int, int>> v;
int cc = cccc;
for (int i = 0; i < t; i++) {
int x; cin >> x;
int cur = n + i + 1;
jump[0][cur] = x, d[cur] = d[x] + 1, in[cur] = in[x];
v.push_back({in[cur], cur});
cc++;
if (adj[x].size() == 1) cc--;
cnt++;
}
if (cc % 2) {
cout << "-1\n";
continue;
}
for (int i = 1; i < 18; i++) {
for (int j = n + 1; j <= n + t; j++) jump[i][j] = jump[i - 1][jump[i - 1][j]];
}
vis[rt] = 1;
for (int i = 0; i < v.size() - 1; i++) {
int x = v[i].S, y = v[i + 1].S;
int w = lca(x, y);
if (vis[w]) continue;
vis[w] = 1;
v.push_back({in[w], w});
}
v.push_back({0, rt});
sort(v.begin(), v.end());
vector<int> stck;
stck.push_back(rt);
for (int i = 1; i < v.size(); i++) {
while (stck.size() && lca(stck.back(), v[i].S) != stck.back()) stck.pop_back();
vrt[stck.back()].push_back(v[i].S);
stck.push_back(v[i].S);
}
answer(rt);
cout << cnt + ans << '\n';
for (auto [_, i] : v) {
vis[i] = 0;
vrt[i].clear();
}
for (int i = n + 1; i <= n + t; i++) {
for (int j = 0; j < 18; j++) jump[j][i] = 0;
in[i] = d[i] = 0;
}
cnt = 0;
}
}
