#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pu push_back
typedef pair <long,long> ii;
const int N=1e6;
long long mod=1e9;
int n;
int a[N+1],d[N+1],sz[N+1],pa[N+1],head[N+1],pos[N+1],arr[N+1],curchain=1,chainid[N+1],curpos=1,ss[N+10],ans,lazy[N*4+10],root,res,lnum;
vector <int> adj[N+1];
bool leaf[N+10],o[N+10];
struct Node{
int c1,c2;
Node operator + (const Node &o) const{
return {c1+o.c1,c2+o.c2};
}
};
Node node[4*N+1];
void dfs(int u,int p){
sz[u]=1;
if(adj[u].size()==1 and p){
ss[u]=1;
leaf[u]=true;
o[u]=true;
lnum++;
}
for(auto v:adj[u]){
if(v==p) continue;
pa[v]=u;
d[v]=d[u]+1;
dfs(v,u);
sz[u]+=sz[v];
ss[u]+=ss[v];
}
}
void hld(int u,int p){
if(head[curchain]==0) head[curchain]=u;
chainid[u]=curchain;
pos[u]=curpos;
arr[curpos]=u;
curpos++;
int nxt=0;
for(auto v:adj[u]){
if(v==p) continue;
if(nxt==0 || sz[v]>sz[nxt]) nxt=v;
}
if(nxt)
hld(nxt,u);
for(auto v:adj[u]){
if(v!=p && v!=nxt){
curchain++;
hld(v,u);
}
}
}
int lca(int u,int v){
while(chainid[u]!=chainid[v]){
if(chainid[u]>chainid[v])
u=pa[head[chainid[u]]];
else
v=pa[head[chainid[v]]];
}
if(d[u]>d[v]) return v;
else return u;
}
void add(int id,int w){
if(w%2==1){
ans-=node[id].c1+node[id].c2*2;
swap(node[id].c1,node[id].c2);
ans+=node[id].c1+node[id].c2*2;
lazy[id]+=w;
}
}
void down(int id){
int t=lazy[id];
add(id*2,t);
add(id*2+1,t);
lazy[id]=0;
}
void Build(int id,int l,int r){
if(l==r){
if(arr[l]==root) return;
node[id].c1=(ss[arr[l]]%2==1);
node[id].c2=(ss[arr[l]]%2==0);
res+=node[id].c1+node[id].c2*2;
return;
}
int mid=(l+r)/2;
Build(id*2,l,mid);
Build(id*2+1,mid+1,r);
node[id]=node[id*2]+node[id*2+1];
}
void Update(int id,int l,int r,int u,int v){
if(l>v or r<u) return;
if(l>=u and r<=v){
add(id,1);
return;
}
down(id);
int mid=(l+r)/2;
Update(id*2,l,mid,u,v);
Update(id*2+1,mid+1,r,u,v);
node[id]=node[id*2]+node[id*2+1];
}
void Upd(int u,int v){
int x=lca(u,v);
while(chainid[u]!=chainid[x]){
Update(1,1,n,pos[head[chainid[u]]],pos[u]);
u=pa[head[chainid[u]]];
}
while(chainid[v]!=chainid[x]){
Update(1,1,n,pos[head[chainid[v]]],pos[v]);
v=pa[head[chainid[v]]];
}
if(d[u]>d[v]){
Update(1,1,n,pos[v],pos[u]);
}
else
Update(1,1,n,pos[u],pos[v]);
}
void tinh(){
int q;
cin>>n;
cin>>q;
for(int i=1;i<n;i++){
int u,v;
cin>>u>>v;
adj[u].pu(v);
adj[v].pu(u);
}
root=1;
for(int i=1;i<=n;i++){
if(adj[i].size()>1){
root=i;
break;
}
}
dfs(root,0);
hld(root,0);
Build(1,1,n);
//cout<<res<<" "<<root<<'\n';
while(q--){
ans=res;
int k;
cin>>k;
int l2=lnum;
vector <int> z;
for(int i=1;i<=k;i++){
cin>>a[i];
ans++;
//out<<ans<<" "<<a[i]<<'\n';
if(a[i]==root) {
l2++;
continue ;
}
if(o[a[i]]){
o[a[i]]=false;
}
else{
l2++;
Upd(root,a[i]);
z.pu(a[i]);
}
//cout<<ans<<" ";
}
if(l2%2==1){
cout<<-1<<'\n';
for(int x:z) Upd(root,x);
continue;
}
cout<<ans<<'\n';
for(int i=1;i<=k;i++){
if(leaf[a[i]]) o[a[i]]=true;
}
for(int x:z) Upd(root,x);
}
}
int main(){
//freopen("jday.inp","r",stdin);
//freopen("jday.out","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
tinh();
return 0;
}
//code của anh Nam đẹp trai nhất CHL
