#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define all(s) s.begin(),s.end()
#define rall(s) s.rbegin(),s.rend()
const ll N=2e5+5;
ll n,q,sub[N],par[N],even=0;
vector<ll>g[N];
void recalc(ll x){
if(sub[x]%2==0) even--;
sub[x]=(g[x].size()==1&&x==1?1:0);
for(ll y:g[x]){
if(y!=par[x]){
sub[x]+=sub[y];
}
}
if(sub[x]%2==0) even++;
}
void find_par(ll x,ll p){
par[x]=p;
for(ll y:g[x]){
if(y!=p){
find_par(y,x);
}
}
}
void dfs(ll x,ll p){
sub[x]=0;
if(g[x].size()==1) sub[x]=1;
for(ll y:g[x]){
if(y!=p){
dfs(y,x);
sub[x]+=sub[y];
}
}
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>n>>q;
for(ll i=1;i<n;i++){
ll u,v;
cin>>u>>v;
g[u].pb(v);
g[v].pb(u);
}
find_par(1,1);
dfs(1,1);
for(ll i=2;i<=n;i++){
if(sub[i]%2==0){
even++;
}
}
while(q--){
ll d;
cin>>d;
vector<ll>a(d);
for(ll i=0;i<d;i++){
cin>>a[i];
g[a[i]].pb(n+i+1);
g[n+i+1].pb(a[i]);
sub[n+i+1]++;
ll x=a[i];
do{
recalc(x);
x=par[x];
}while(x!=1);
}
if(sub[1]&1){
cout<<-1<<"\n";
}
else{
cout<<even+n+d-1<<"\n";
}
for(ll i=d-1;i>=0;i--){
g[a[i]].pop_back();
g[n+i+1].pop_back();
sub[n+i+1]=0;
ll x=a[i];
do{
recalc(x);
x=par[x];
}while(x!=1);
}
}
}
