#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N=2e5+5;
int n,q,id,ans,depth[N],sz[N],leafs[N],hv[N],head[N],par[N],idx[N],idxdeg[N];
int rt=1;
bool leaf[N];
vector<vector<int>> adj(N);
struct {
struct node{
int odd,even,lz; // #times that use edge(par[i],i), ans for subtree, lazypropagation
node():odd(0),even(0),lz(0){}
};
node seg[4*N];
void push(int l,int r,int i){
if(seg[i].lz){
seg[i].lz=false;
swap(seg[i].odd,seg[i].even);
if(l!=r){
seg[2*i].lz^=1;
seg[2*i+1].lz^=1;
}
}
}
void build(int l,int r,int i){
if(l==r){
if(idxdeg[l]) seg[i].odd++;
else seg[i].even++;
return;
}
int mid=(l+r)/2;
build(l,mid,2*i),build(mid+1,r,2*i+1);
seg[i].odd=seg[2*i].odd+seg[2*i+1].odd;
seg[i].even=seg[2*i].even+seg[2*i+1].even;
}
void update(int l,int r,int i,int ll,int rr){
push(l,r,i);
if(r<ll||l>rr) return;
if(l>=ll&&r<=rr) return seg[i].lz=1,push(l,r,i),void();
int mid=(l+r)/2;
update(l,mid,2*i,ll,rr),update(mid+1,r,2*i+1,ll,rr);
seg[i].odd=seg[2*i].odd+seg[2*i+1].odd;
seg[i].even=seg[2*i].even+seg[2*i+1].even;
}
void add(int x){
while(1){
update(1, n, 1, idx[head[x]], idx[x]);
if(head[x]==rt) break;
x=par[head[x]];
}
}
int query(){
push(1,n,1);
return seg[1].odd+2*seg[1].even;
}
} lazyseg;
int dfs1(int u,int p){
par[u]=p;
depth[u]=depth[p]+1;
sz[u]++;
leafs[u]=leaf[u];
int mx=0;
for(auto v:adj[u]){
if(v==p) continue;
sz[u]+=dfs1(v,u);
leafs[u]+=leafs[v];
if(sz[v]>mx){
mx=sz[v];
hv[u]=v;
}
}
return sz[u];
}
void hld(int u,int p,int h){
idx[u]=++id;
head[u]=h;
if(hv[u]) hld(hv[u],u,h);
for(auto v:adj[u]){
if(v==p||v==hv[u]) continue;
hld(v,u,v);
}
}
void calculatedfs(int u,int p){
for(int i=1; i<=n; i++){
idxdeg[idx[i]]=leafs[i]%2;
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> q;
for(int i=1; i<n; i++){
int u, v;
cin >> u >> v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
for(int i=n; i>=1; i--){
if(adj[i].size()==1) leaf[i]=true;
else rt=i,leaf[i]=false;
}
dfs1(rt,rt);
hld(rt,rt,rt);
calculatedfs(rt,rt);
lazyseg.build(1,n,1);
int __=1;
bool visited[n+1]; memset(visited, 0, sizeof visited);
while(__++<=q){
int d;
cin >> d;
int que[d];
for(auto &e:que) cin >> e;
int cnt=0;
for(int i=0; i<d; i++){
if(leaf[que[i]]&&!visited[que[i]]) visited[que[i]]=true,cnt++;
else lazyseg.add(que[i]);
}
int le=leafs[rt]+d-cnt;
if(le%2) cout << -1 << "\n";
else cout << lazyseg.query()+d-2 << "\n";
for(auto e:que){
if(leaf[e] && visited[e]) visited[e] = false;
else lazyseg.add(e);
}
}
}
