#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;
vector<ll> in;
vector<ll> out;
const int maxn=4e5+3;
int tree[maxn];
void update(ll node, ll l, ll r, ll pos, ll val)
{
if(pos > r || pos < l)
{
return;
}
if(l==r)
{
tree[node]=val;
return;
}
ll mid=(l+r)>>1;
update(node*2+1,l,mid,pos,val);
update(node*2+2,mid+1,r,pos,val);
tree[node]=tree[node*2+1]+tree[node*2+2];
}
ll query(ll node, ll l, ll r, ll x, ll y)
{
if(max(l,x) > min(r,y))
{
return 0;
}
if(l==r)
{
return tree[node];
}
ll mid=(l+r)>>1;
return query(node*2+1,l,mid,x,y)+query(node*2+2,mid+1,r,x,y);
}
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 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);
for (int i=0;i<maxn;i++) tree[i]=0;
ll n, q;
cin>>n>>q;
vector<vector<ll>> adj(n);
value.resize(n);
in.resize(n);
out.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);
ll time=0;
dfs(0,0,0,adj,parr,time);
dbg(old);
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);
}
sort(arr.begin(), arr.end());
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;
for (auto &&e : v)
{
update(0,0,n-1,in[e],1);
}
for (auto &&e : v)
{
ll vl=query(0,0,n-1,in[e],out[e])-1;
if(vl%2)
{
ans-=value[e];
}
else
{
ans+=value[e];
}
}
cout << ans << endl;
for (auto &&e : v)
{
update(0,0,n-1,in[e],0);
}
}
}
}
