#include<bits/stdc++.h>
using namespace std;
vector<int>adj[100005];
int sz[100005],hv[100005],hd[100005],pa[100005],in[100005],out[100005];
int cur=0;
int val[100005];
int n,q;
int cnt=0;
int rt=0;
int isl[100005];
struct segtree{
int info[400005];
int lz[400006];
void push(int st,int en,int i){
if(lz[i]==0)return;
info[i]=(en-st+1-info[i]);
if(st!=en)lz[i*2]^=lz[i],lz[i*2+1]^=lz[i];
lz[i]=0;
}
void inv(int st,int en,int i,int l,int r){
push(st,en,i);
if(st>r||en<l)return;
if(st>=l&&en<=r)return lz[i]=1,push(st,en,i);
int m=(st+en)/2;
inv(st,m,i*2,l,r);
inv(m+1,en,i*2+1,l,r);
info[i]=info[i*2]+info[i*2+1];
}
void build(int st,int en,int i){
if(st==en){
return void(info[i]=val[st]);
}
int m=(st+en)/2;
build(st,m,i*2);
build(m+1,en,i*2+1);
info[i]=info[i*2]+info[i*2+1];
//cerr<<"info:"<<i<<" "<<info[i*2]<<"+"<<info[i*2+1]<<"\n";
}
}tr;
void dfssz(int u,int p){
sz[u]=1;
for(auto x:adj[u]){
if(x==p)continue;
dfssz(x,u);
sz[u]+=sz[x];
if(sz[hv[u]]<sz[x])hv[u]=x;
}
}
void dfs(int u,int p,int h){
in[u]=++cur;
//cerr<<"in:"<<u<<" "<<in[u]<<"\n";
hd[u]=h;
pa[u]=p;
if(hv[u])dfs(hv[u],u,h);
for(auto x:adj[u])if(x!=p&&x!=hv[u]){
dfs(x,u,x);
}
out[u]=cur;
}
void init(int u,int p){
int ch=0;
for(auto x:adj[u])if(x!=p){
init(x,u);
val[in[u]]^=val[in[x]];
ch++;
}
if(ch==0){
val[in[u]]=1;
cnt++;
isl[u]=1;
//cerr<<"ch:"<<u<<"\n";
}
//cerr<<"val:"<<u<<" "<<val[in[u]]<<"\n";
}
void rv(int x){
int temp=x;
//cerr<<"Rv:"<<temp<<"\n";
while(temp){
int h=hd[temp];
tr.inv(1,n,1,in[h],in[temp]);
//cerr<<in[h]<<" "<<in[temp]<<"\n";
temp=pa[h];
}
}
int vis[100005];
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cin>>n>>q;
for(int i=1;i<n;i++){
int u,v;cin>>u>>v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for(int i=1;i<=n;i++)if(adj[i].size()!=1){
rt=i;
break;
}
//cerr<<"rt:"<<rt<<"\n";
dfssz(rt,0);
dfs(rt,0,rt);
init(rt,0);
tr.build(1,n,1);
//cerr<<"work\n";
//cerr<<cnt<<"\n";
//cerr<<tr.info[1]<<"\n";
for(int i=0;i<q;i++){
int d;cin>>d;
vector<int>v;
vector<int>lf;
int temp=cnt;
for(int j=0;j<d;j++){
int x;cin>>x;
temp++;
if(isl[x]&&vis[x]==0)temp--,lf.push_back(x),vis[x]=1;
else{
v.push_back(x);
rv(x);
//cerr<<"rv:"<<x<<"\n";
}
}
//cerr<<"Q:"<<temp<<"\n";
if(temp%2==0)cout<<(2*(n-1)-tr.info[1]+d)<<"\n";
else cout<<"-1\n";
for(auto x:lf)vis[x]=0;
for(auto x:v)rv(x);
}
}
