#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
#define pb push_back
const int N = 200050;
int deg[N];
vector<int> E[N];
const int M = 2 * N;
int root, ls[M], rs[M], sum[M], tsz, lzy[M];
void Flip(int &c, int ss, int se, int qs, int qe) {
if (qs > qe || qs > se || ss > qe) return;
if (!c) c = ++tsz;
if (qs <= ss && qe >= se) {
sum[c] = se - ss + 1 - sum[c];
lzy[c] ^= 1;
return;
}
int mid = ss + se >> 1;
Flip(ls[c], ss, mid, qs, qe);
Flip(rs[c], mid + 1, se, qs, qe);
sum[c] = sum[ls[c]] + sum[rs[c]];
if (lzy[c]) sum[c] = se - ss + 1 - sum[c];
}
int head[N], lid[N], rid[N], tid, sz[N], par[N];
void DFS(int u, int p) {
sz[u] = 1;
par[u] = p;
for (int v : E[u]) if (v != p) DFS(v, u), sz[u] += sz[v];
}
void HLD(int u, int p) {
lid[u] = ++tid;
if (!head[u]) head[u] = u;
int hc = 0;
for (int v : E[u]) if (v != p && sz[hc] < sz[v]) hc = v;
if (hc != 0) {
head[hc] = head[u];
HLD(hc, u);
for (int v : E[u]) if (v != p && v != hc) HLD(v, u);
}
rid[u] = tid;
}
void Flip(int u) {
while (u > 0) {
Flip(root, 2, tid, lid[head[u]], lid[u]);
u = par[head[u]];
}
}
int main() {
int n, q;
cin >> n >> q;
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
E[u].pb(v);
E[v].pb(u);
deg[u]++;
deg[v]++;
}
DFS(1, 0);
HLD(1, 0);
int leaf = 0;
for (int i = 1; i <= n; i++) if (deg[i] == 1) Flip(i), leaf++;
for (int i = 1; i <= q; i++) {
int k;
cin >> k;
vector<int> p(k);
for (int &j : p) {
cin >> j;
deg[j]++;
if (deg[j] != 2) {
leaf++;
Flip(j);
}
}
if (leaf % 2 == 1) cout << "-1\n";
else cout << n - 1 + k + n - 1 - sum[root] << '\n';
reverse(p.begin(), p.end());
for (int j : p) {
deg[j]--;
if (deg[j] != 1) {
leaf--;
Flip(j);
}
}
}
return 0;
}
