#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define int long long
const int MAXN = 100005;
const int LOG = 20;
int n, q;
int depth[MAXN], t[LOG][MAXN];
int entry[MAXN], exsi[MAXN], siz[MAXN];
int ent = 0, exs = 0;
int Oans = 0;
array<int,2> pre[MAXN];
vector<int> v[MAXN], vr[MAXN];
int marked[MAXN];
int timerMark = 1;
bool is_ancestor(int a, int b){
return entry[a] <= entry[b] && exsi[b] <= exsi[a];
}
int LCA(int a, int b){
if(depth[a] < depth[b]) swap(a,b);
int k = depth[a] - depth[b];
for(int bt = LOG-1; bt >= 0; bt--){
if(k >= (1LL << bt)){
k -= (1LL << bt);
a = t[bt][a];
}
}
if(a == b) return a;
for(int bt = LOG-1; bt >= 0; bt--){
if(t[bt][a] != t[bt][b]){
a = t[bt][a];
b = t[bt][b];
}
}
return t[0][a];
}
void dfs1(int i, int last){
if((int)v[i].size() == 1) siz[i] = 1;
for(int j : v[i]){
if(j == last) continue;
dfs1(j, i);
siz[i] = (siz[i] + siz[j]) % 2;
}
if(i != 1){
Oans += 2 - (siz[i] % 2);
}
}
void dfs2(int i, int last){
t[0][i] = last;
depth[i] = depth[last] + 1;
entry[i] = ent++;
if(i == 1){
pre[0][i] = 0;
pre[1][i] = 0;
}
else{
pre[0][i] = pre[0][last] + (1 - (siz[i] % 2));
pre[1][i] = pre[1][last] + (siz[i] % 2);
}
for(int j : v[i]){
if(j == last) continue;
dfs2(j, i);
}
exsi[i] = exs++;
}
array<int,2> calc(int i, int last){
array<int,2> ans = {0, 0};
if(marked[i] == timerMark){
ans[1] = 1;
}
for(int j : vr[i]){
array<int,2> a = calc(j, i);
ans[0] += a[0];
ans[1] ^= a[1];
}
if(i != 1 && ans[1] == 1){
ans[0] += (pre[1][i] - pre[1][last]) - (pre[0][i] - pre[0][last]);
}
return ans;
}
int answer_virtual(vector<int> leafs){
timerMark++;
vector<int> nodes;
nodes.push_back(1);
for(int x : leafs){
marked[x] = timerMark;
nodes.push_back(x);
}
sort(nodes.begin(), nodes.end(), [&](int a, int b){
return entry[a] < entry[b];
});
int sz = nodes.size();
for(int i = 1; i < sz; i++){
nodes.push_back(LCA(nodes[i-1], nodes[i]));
}
sort(nodes.begin(), nodes.end(), [&](int a, int b){
return entry[a] < entry[b];
});
nodes.erase(unique(nodes.begin(), nodes.end()), nodes.end());
vector<int> st;
for(int x : nodes){
while(!st.empty() && !is_ancestor(st.back(), x)){
st.pop_back();
}
if(!st.empty()){
vr[st.back()].push_back(x);
}
st.push_back(x);
}
array<int,2> u = calc(1, 0);
int ans = Oans + u[0];
for(int x : nodes){
vr[x].clear();
}
return ans;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> q;
for(int i = 0; i < n - 1; i++){
int a, b;
cin >> a >> b;
v[a].push_back(b);
v[b].push_back(a);
}
dfs1(1, 0);
dfs2(1, 0);
for(int bt = 1; bt < LOG; bt++){
for(int i = 1; i <= n; i++){
t[bt][i] = t[bt-1][t[bt-1][i]];
}
}
while(q--){
int k;
cin >> k;
vector<int> vc(k);
for(int i = 0; i < k; i++){
cin >> vc[i];
}
if(k == 0){
if(siz[1] % 2 == 1){
cout << -1 << endl;
}
else{
cout << Oans << endl;
}
continue;
}
sort(vc.begin(), vc.end());
vector<int> leafs;
int cnt = 0;
for(int i = 0; i < k; ){
int x = vc[i];
int j = i;
while(j < k && vc[j] == x){
j++;
}
int fre = j - i;
bool originalLeaf = ((int)v[x].size() == 1);
if(originalLeaf){
cnt++;
if(fre % 2 == 0){
leafs.push_back(x);
}
}
else{
if(fre % 2 == 1){
leafs.push_back(x);
}
}
i = j;
}
int finalLeafParity = (siz[1] + k - cnt) % 2;
if(finalLeafParity == 1){
cout << -1 << endl;
}
else{
cout << answer_virtual(leafs) + k << endl;
}
}
return 0;
}
