#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;
}
vector<ll> value;
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)
{
if(node!=0)
{
if(parr[node].second)
{
cur++;
}
else cur--;
}
value[node]=cur;
for (auto &&e : adj[node])
{
if(e==par) continue;
dfs(e,node,cur,adj,parr);
}
}
void tl3(ll node, vector<pair<ll,ll>>& parr, ll& ans)
{
while(node!=0)
{
if(parr[node].second==0)ans--;
else ans++;
parr[node].second^=1;
node=parr[node].first;
}
}
int main()
{
cin.tie(0);
ios_base::sync_with_stdio(false);
ll n, q;
cin>>n>>q;
vector<vector<ll>> adj(n);
value.resize(n);
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);
dfs(0,0,0,adj,parr);
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--;
if(adj[nd].size()!=1)
{
val++;
ans+=value[nd];
}
ans++;
}
if(val%2) cout<<-1<<endl;
else cout << ans << endl;
}
}
