#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define mod 1000000007
#define int long long
int n,q;
int arr[100005],depth[100005],t[20][100005],entry[100005],exsi[100005],siz[100005],ent,exs,Oans;
array <int,2> pre[100005];
vector <int> v[100005],vr[100005];
int LCA(int a,int b){
if(depth[a]<depth[b]){
swap(a,b);
}
int k=depth[a]-depth[b];
for(int bt=19;bt>=0;bt--){
if(k-(1ll<<bt)>=0){
k-=(1ll<<bt);
a=t[bt][a];
}
}
for(int bt=19;bt>=0;bt--){
if(t[bt][a]!=t[bt][b]){
a=t[bt][a];
b=t[bt][b];
}
}
if(a==b) return a;
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;
return;
}
void dfs2(int i,int last){
t[0][i]=last;
depth[i]=depth[t[0][i]]+1;
entry[i]=ent++;
for(int j:v[i]){
if(j==last) continue;
dfs2(j,i);
}
pre[0][i]=pre[0][last]+(1-siz[i]%2);
pre[1][i]=pre[1][last]+siz[i]%2;
exsi[i]=exs++;
return;
}
array <int,2> calc(int i,int last){
array <int,2> ans={0,0};
if(vr[i].size()==0) ans[1]=1;
for(int j:vr[i]){
array <int,2> a=calc(j,i);
ans[0]+=a[0];ans[1]=(ans[1]+a[1])%2;
}
if(i!=1){
if(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){
set <array<int,2>> ord;
for(int i=0;i<leafs.size();i++){
ord.insert({entry[leafs[i]],leafs[i]});
if(i!=0){
int C=LCA(leafs[i],leafs[i-1]);
ord.insert({entry[C],C});
}
}
ord.insert({entry[1],1});
vector <int> stack;
int rt;
for(auto [idx,i]:ord){
if(stack.size()==0){
rt=i;
stack.push_back(i);
}
else{
while(exsi[i]>exsi[stack.back()]||entry[i]<entry[stack.back()]){
stack.pop_back();
}
vr[stack.back()].push_back(i);
stack.push_back(i);
}
}
array <int,2> u=calc(rt,0);
int ans=Oans+u[0];
for(auto [idx,i]:ord){
vr[i].clear();
}
return ans;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.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<=19;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> leafs;
int cnt=0;
for(int i=0;i<k;i++){
int a;cin>>a;
if(v[a].size()==1) cnt++;
else leafs.push_back(a);
}
if((siz[1]+(int)leafs.size())%2==1) cout<<-1<<endl;
else cout<<answer_virtual(leafs)+(int)leafs.size()+cnt<<endl;;
leafs.clear();
}
return 0;
}
