#include<bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
const int TAILLEMAXI=200*1000+2;
int nbnoeuds,nbquest;
vector<int> adja[TAILLEMAXI];
vector<int> nouv[TAILLEMAXI];
int racine;
pair<int,int> dp(int a,int vient){ // nb feuilles, cout
if (nouv[a].size()==1){
return {1,1};
}
pair<int,int> total={0,0};
for (auto v:nouv[a]){
if (v!=vient){
pair<int,int> enfant=dp(v,a);
total.first+=enfant.first;
total.second+=enfant.second;
}
}
if (a!=racine){
if (total.first%2==1){
return {1,total.second+1};
}
return {2,total.second+2};
}
return total;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>nbnoeuds>>nbquest;
for (int i=0;i<nbnoeuds-1;i++){
int a,b;
cin>>a>>b;
a--;
b--;
adja[a].push_back(b);
adja[b].push_back(a);
}
racine=-1;
int indice=0;
while (racine==-1){
if (adja[indice].size()!=1){
racine=indice;
}
indice++;
}
for (int i=0;i<nbquest;i++){
int enplus;
cin>>enplus;
for (int j=0;j<nbnoeuds+enplus;j++){
nouv[j]=adja[j];
}
for (int j=0;j<enplus;j++){
int val;
cin>>val;
nouv[val-1].push_back(nbnoeuds+j);
nouv[nbnoeuds+j].push_back(val-1);
}
int nbfeuilles=0;
for (int j=0;j<nbnoeuds+enplus;j++){
if (nouv[j].size()==1){
nbfeuilles++;
}
}
if (nbfeuilles%2==1){
cout<<-1<<endl;
}
else {
cout<<dp(racine,-1).second<<endl;
}
}
return 0;
}
