#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
using namespace std;
int N, Q, leaf[100005], lvs[100005], depth[100005], evens[100005], jp[18][100005], rawtot, seen[100005];
int sz[100005], ind[100005], offset[100005], cnt, newans;
vector<int> graph[100005], g2[100005];
vector<int> nl, newnodes, comps;
void dfs1(int x, int p) {
//printf("dfs1(%d, %d)\n", x, p);
leaf[x] = 1;
ind[x] = cnt++;
sz[x] = 1;
jp[0][x] = p;
for (int v : graph[x]) {
if (v != p) {
leaf[x] = 0;
depth[v] = depth[x] + 1;
dfs1(v, x);
lvs[x] += lvs[v];
sz[x] += sz[v];
}
}
if (x == 1 && graph[x].size() <= 1) leaf[x] = 1;
lvs[x] += leaf[x];
}
void dfs2(int x, int p) {
if (x != 1) rawtot += 1 + ((lvs[x] % 2) ^ 1);
evens[x] += ((lvs[x] % 2) ^ 1);
for (int v : graph[x]) {
if (v != p) {
evens[v] = evens[x];
dfs2(v, x);
}
}
}
void dfs3(int x, int p) {
//printf("dfs3(%d, %d)\n", x, p);
for (int v : g2[x]) {
dfs3(v, x);
offset[x] += offset[v];
}
if (offset[x] & 1) {
newans += depth[x] - depth[p] - 2 * (evens[x] - evens[p]);
}
}
int isanc(int a, int b) {
return ind[a] <= ind[b] && ind[a] + sz[a] > ind[b];
}
int lca(int u, int v) {
if (isanc(u, v)) return u;
if (isanc(v, u)) return v;
int cur = u;
for (int i = 17; i >= 0; i--) {
if (!isanc(jp[i][cur], v)) cur = jp[i][cur];
}
return jp[0][cur];
}
int main() {
scanf("%d %d", &N, &Q);
for (int i = 0; i < N-1; i++) {
int u, v;
scanf("%d %d", &u, &v);
graph[u].push_back(v);
graph[v].push_back(u);
}
dfs1(1, 1);
dfs2(1, 1);
for (int b = 1; b < 18; b++) {
for (int i = 1; i <= N; i++) {
jp[b][i] = jp[b-1][jp[b-1][i]];
}
}
for (int q = 0; q < Q; q++) {
//printf("==========\n");
int d;
scanf("%d", &d);
nl.clear();
for (int i = 0; i < d; i++) {
int a;
scanf("%d", &a);
nl.push_back(a);
}
int createdleaves = 0;
sort(nl.begin(), nl.end(), [](int l, int r){
return ind[l] < ind[r];
});
for (int i = 0; i < nl.size(); i++) {
if (i > 0 && nl[i-1] == nl[i]) {
offset[nl[i]]++;
createdleaves++;
} else {
//printf("new node: %d\n", nl[i]);
seen[nl[i]] = 1;
newnodes.push_back(nl[i]);
if (i == 0) {
comps.push_back(nl[i]);
} else {
int l = lca(nl[i], nl[i-1]);
if (!seen[l]) newnodes.push_back(l);
seen[l] = 1;
if (l != nl[i-1]) {
while (comps.size() && depth[l] < depth[comps.back()]) {
if (comps.size() > 1 && depth[comps[comps.size() - 2]] > depth[l]) {
g2[comps[comps.size() - 2]].push_back(comps.back());
//printf("Added compressed tree edge %d -> %d\n", comps[comps.size() - 2], comps.back());
} else {
g2[l].push_back(comps.back());
//printf("Added compressed tree edge %d -> %d\n", l, comps.back());
}
comps.pop_back();
}
if (comps.empty() || comps.back() != l) comps.push_back(l);
}
comps.push_back(nl[i]);
}
if (!leaf[nl[i]]) createdleaves++;
offset[nl[i]] = 1 - leaf[nl[i]];
}
}
while (comps.size() > 1) {
g2[comps[comps.size()-2]].push_back(comps.back());
//printf("Added compressed tree edge %d -> %d\n", comps[comps.size() - 2], comps.back());
comps.pop_back();
}
newans = rawtot + d;
dfs3(comps[0], 1);
if ((createdleaves + lvs[1]) & 1) {
printf("-1\n");
} else {
printf("%d\n", newans);
}
// CLEANUP!!!
newans = 0;
for (int v : newnodes) {
//printf("New nodes: %d\n", v);
g2[v].clear();
offset[v] = 0;
seen[v] = 0;
}
newnodes.clear();
comps.clear();
}
}
