#include <bits/stdc++.h>
#define ll long long
#define dbg(x) cerr << #x << ' ' << x << endl;
#define inf 1e18
using namespace std;
void printvec(vector<ll>& vec)
{
for (auto &&e : vec)
{
cout << e << ' ';
}
cout << endl;
}
const int maxn = 2e4+1;
int value[maxn];
int in[maxn];
int out[maxn];
int arr2[maxn];
const int lg=18;
int up[maxn][lg];
ll solve(vector<vector<ll>>& adj, ll node, ll par, ll& ans,vector<pair<ll,ll>>& parr)
{
if(node!=par && adj[node].size()==1)
{
parr[node]={par,1};
if(node!=0)
{
if(parr[node].second==0) ans+=2;
else ans++;
}
return 1;
}
ll sm=0;
for (auto &&e : adj[node])
{
if(e==par)continue;
ll val=solve(adj,e,node,ans,parr);
sm+=val;
}
if(adj[node].size()==1 && node==0) sm++;
parr[node]={par,sm%2};
if(node!=0)
{
if(parr[node].second==0) ans+=2;
else ans++;
}
return sm;
}
void dfs(ll node, ll par, ll cur,vector<vector<ll>>& adj, vector<pair<ll,ll>>& parr, ll& time)
{
in[node]=time;
if(node!=0)
{
if(parr[node].second)
{
cur++;
}
else cur--;
}
value[node]=cur;
for (auto &&e : adj[node])
{
if(e==par) continue;
time++;
dfs(e,node,cur,adj,parr,time);
}
out[node] = time;
}
void gadup(ll n, vector<pair<ll,ll>>& parr)
{
for (int i=0;i<n;i++)
{
for (int j=0;j<lg;j++)
{
if(j==0)
{
up[i][j]=parr[i].first;
}
else
{
up[i][j]=up[up[i][j-1]][j-1];
}
}
}
}
bool islca(ll a, ll b)
{
if(in[a] <= in[b] && in[b] <= out[a]) return true;
return false;
}
ll lca(ll u, ll v)
{
if(islca(u,v)) return u;
if(islca(v,u)) return v;
for (int j=lg-1;j>=0;j--)
{
if(!(islca(up[u][j],v)))
{
u=up[u][j];
}
}
u=up[u][0];
return u;
}
ll dfs2(ll& ans, ll node, ll par, vector<vector<ll>>& adj)
{
if(node!=0 && adj[node].size()==1) return arr2[node];
ll val=arr2[node];
for (auto &&e : adj[node])
{
if(e==par) continue;
ll qry=dfs2(ans,e,node,adj);
val+=qry;
if(qry%2)
{
ans+=value[e]-value[node];
}
}
return val;
}
int main()
{
cin.tie(0);
ios_base::sync_with_stdio(false);
ll n, q;
cin>>n>>q;
for (int i=0;i<maxn;i++)
{
arr2[i]=0;
}
vector<vector<ll>> adj(n);
value[0]=0;
for (int i=0;i<n-1;i++)
{
ll u, v;
cin>>u>>v;
u--;v--;
adj[u].push_back(v);
adj[v].push_back(u);
}
ll old=0;
ll leaves=0;
for (int i=0;i<n;i++)
{
leaves+=adj[i].size()==1;
}
vector<pair<ll,ll>> parr(n);
solve(adj,0,0,old,parr);
ll time=0;
dfs(0,0,0,adj,parr,time);
gadup(n,parr);
vector<vector<ll>> adj2(n);
while(q--)
{
ll d;
cin>>d;
vector<ll> v;
vector<ll> arr;
ll ans=old;
ll val=leaves;
for (int i=0;i<d;i++)
{
ll nd;
cin>>nd;
nd--;
arr.push_back(nd);
}
auto comp=[&](ll a, ll b){return in[a]<in[b];};
sort(arr.begin(), arr.end(),comp);
ll cur=0;
for (int i=0;i<d;i++)
{
cur++;
if(i==d-1 || arr[i+1]!=arr[i])
{
if(adj[arr[i]].size()==1)
{
cur--;
}
if(cur%2) v.push_back(arr[i]);
cur=0;
}
}
val+=v.size();
if(val%2) cout<<-1<<endl;
else
{
ans+=d;
vector<ll> v2;
for (auto &&e : v)
{
arr2[e]=1;
v2.push_back(e);
}
ll sz=v.size();
for (int i=0;i<sz-1;i++)
{
v.push_back(lca(v[i],v[i+1]));
}
v.push_back(0);
sort(v.begin(), v.end(),comp);
v.erase(unique(v.begin(),v.end()),v.end());
for (int i=0;i<v.size()-1;i++)
{
ll l=lca(v[i],v[i+1]);
adj2[v[i+1]].push_back(l);
adj2[l].push_back(v[i+1]);
}
dfs2(ans,0,0,adj2);
cout << ans << endl;
for (auto &&e : v)
{
adj2[e].clear();
}
for (auto &&e : v2)
{
arr2[e]=0;
}
}
}
}
