#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 2e5;
int N, Q, M;
vector<int> adj[MAXN+10];
int dp[MAXN+10], par[MAXN+10][30], dep[MAXN+10], leaf, cnt[MAXN+10], val, root;
int L[MAXN+10], R[MAXN+10], dfn;
pii dp2[MAXN+10];
void dfs(int now, int bef, int d)
{
L[now]=++dfn;
par[now][0]=bef;
dep[now]=d;
dp[now]=0;
if(adj[now].size()==1)
{
dp[now]=1;
R[now]=dfn;
return;
}
for(int nxt : adj[now])
{
if(nxt==bef) continue;
dfs(nxt, now, d+1);
dp[now]+=dp[nxt];
dp[now]%=2;
}
R[now]=dfn;
}
pii operator + (const pii &p, const pii &q) { return {p.first+q.first, p.second+q.second}; }
pii operator - (const pii &p, const pii &q) { return {p.first-q.first, p.second-q.second}; }
void dfs2(int now, int bef, pii val)
{
if(now!=bef)
{
if(dp[now]==0) val.first++;
else if(dp[now]==1) val.second++;
}
dp2[now]=val;
for(int nxt : adj[now])
{
if(nxt==bef) continue;
dfs2(nxt, now, val);
}
}
int lca(int u, int v)
{
if(dep[u]>dep[v]) swap(u, v);
for(int i=20; i>=0; i--) if(dep[par[v][i]]>=dep[u]) v=par[v][i];
if(u==v) return u;
for(int i=20; i>=0; i--) if(par[u][i]!=par[v][i]) u=par[u][i], v=par[v][i];
return par[u][0];
}
int dp3[MAXN+10];
vector<int> adj2[MAXN+10];
int ans=0;
void dfs3(int now, int bef)
{
for(int nxt : adj2[now])
{
if(nxt==bef) continue;
//printf("Edge %d %d\n", nxt, now);
dfs3(nxt, now);
dp3[now]+=dp3[nxt];
dp3[now]%=2;
}
//printf("%d : %d / %d %d\n", now, dp3[now], dp2[now].first, dp2[now].second);
if(now!=bef)
{
if(dp3[now])
{
pii t=dp2[now]-dp2[bef];
ans-=t.first*2+t.second;
ans+=t.first+t.second*2;
}
}
}
int main()
{
scanf("%d%d", &N, &Q);
for(int i=1; i<N; i++)
{
int u, v;
scanf("%d%d", &u, &v);
adj[u].push_back(v);
adj[v].push_back(u);
}
for(int i=1; i<=N; i++) if(adj[i].size()==1) leaf++;
for(int i=1; i<=N; i++) if(adj[i].size()!=1) { root=i; break; }
dfs(root, root, 1);
dfs2(root, root, pii(0, 0));
for(int i=1; i<=N; i++)
{
if(i==root) continue;
if(dp[i]==0) val+=2;
else val+=1;
}
for(int j=1; j<=20; j++) for(int i=1; i<=N; i++) par[i][j]=par[par[i][j-1]][j-1];
while(Q--)
{
scanf("%d", &M);
vector<int> V, V2;
for(int i=1; i<=M; i++)
{
int t;
scanf("%d", &t);
V.push_back(t);
}
sort(V.begin(), V.end()); V2=V;
V2.erase(unique(V2.begin(), V2.end()), V2.end());
int lt=leaf;
for(auto it : V2) if(adj[it].size()==1) lt--;
lt+=M;
if(lt%2) { printf("-1\n"); continue; }
for(auto it : V) cnt[it]++;
vector<int> VV=V2;
sort(VV.begin(), VV.end(), [&](const int &p, const int &q){ return L[p]<L[q]; });
int t=VV.size();
for(int i=0; i+1<t; i++) VV.push_back(lca(VV[i], VV[i+1]));
VV.push_back(root);
sort(VV.begin(), VV.end(), [&](const int &p, const int &q){ return L[p]<L[q]; });
VV.erase(unique(VV.begin(), VV.end()), VV.end());
vector<int> S;
for(int i=0; i<VV.size(); i++)
{
while(!S.empty() && !(L[S.back()]<=L[VV[i]] && R[VV[i]]<=R[S.back()])) S.pop_back();
if(!S.empty()) adj2[S.back()].push_back(VV[i]);
S.push_back(VV[i]);
}
for(auto it : V2)
{
if(adj[it].size()==1) dp3[it]=(cnt[it]-1)%2;
else dp3[it]=cnt[it]%2;
}
ans=val+M;
dfs3(root, root);
printf("%d\n", ans);
for(auto it : V) cnt[it]=0;
for(auto it : VV) adj2[it].clear();
for(auto it : VV) dp3[it]=0;
}
}
