//雪花飄飄北風嘯嘯
//天地一片蒼茫
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define ll long long
#define ii pair<ll,ll>
#define iii pair<ii,ll>
#define fi first
#define se second
#define endl '\n'
#define debug(x) cout << #x << " is " << x << endl
#define rep(x,start,end) for(auto x=(start)-((start)>(end));x!=(end)-((start)>(end));((start)<(end)?x++:x--))
#define all(x) (x).begin(),(x).end()
#define sz(x) (int)(x).size()
#define indexed_set tree<ll,null_type,less<ll>,rb_tree_tag,tree_order_statistics_node_update>
//change less to less_equal for non distinct pbds, but erase will bug
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
int n,q;
vector<int> al[100005];
int in[100005]; //preorder
int out[100005]; //postorder
int st[100005]; //subtree size
int parent[100005]; //first parent
int hparent[100005]; //parent on heavy path
int depth[100005];
bool par[100005];
int extra[100005];
ll ans;
int dfs(int i,int p){
int ropes=0;
if (sz(al[i])==1){
ans+=depth[i];
par[i]=true;
ropes=1;
}
for (auto &it:al[i]){
if (it==p) continue;
depth[it]=depth[i]+1;
ropes+=dfs(it,i);
par[i]^=par[it];
}
while (ropes>2){
ropes-=2;
ans-=2*depth[i];
}
return ropes;
}
void dfs_st(int i,int p){
parent[i]=p;
st[i]=1;
if (al[i][0]==p && al[i].size()>1) swap(al[i][0],al[i][1]);
for (auto &it:al[i]){ ///& is important here
if (it==p) continue;
dfs_st(it,i);
st[i]+=st[it];
if (st[it]>st[al[i][0]]){
swap(it,al[i][0]);
//we ensure heavy child is al[i][0]
}
}
}
int dfs_time=0;
void dfs_hld(int i,int p){
in[i]=++dfs_time;
for (auto it:al[i]){
if (it==p) continue;
hparent[it]=(it==al[i][0])?hparent[i]:it;
dfs_hld(it,i);
}
out[i]=dfs_time;
}
struct node{
int s,e,m;
int bits[2];
bool lazy=false;
node *l,*r;
node (int _s,int _e){
s=_s,e=_e,m=s+e>>1;
bits[0]=bits[1]=0;
if (s!=e){
l=new node(s,m);
r=new node(m+1,e);
}
}
void init(int i,int k){
bits[k]++;
if (s==e) return;
else if (i<=m) l->init(i,k);
else r->init(i,k);
}
void propo(){
if (lazy){
swap(bits[0],bits[1]);
if (s!=e){
l->lazy^=true;
r->lazy^=true;
}
lazy=false;
}
}
void update(int i,int j){
if (s==i && e==j) lazy^=true;
else{
if (j<=m) l->update(i,j);
else if (m<i) r->update(i,j);
else l->update(i,m),r->update(m+1,j);
l->propo(),r->propo();
rep(x,0,2) bits[x]=l->bits[x]+r->bits[x];
}
}
int query(int i,int j){
propo();
if (s==i && e==j) return bits[1];
else if (j<=m) return l->query(i,j);
else if (m<i) return r->query(i,j);
else return l->query(i,m)+r->query(m+1,j);
}
} *root=new node(0,200005);
void hld_query(int i,bool flag){
while (i){
if (flag){
root->update(in[hparent[i]],in[i]);
ans-=2*root->query(in[hparent[i]],in[i]);
}
else{
ans+=2*root->query(in[hparent[i]],in[i]);
root->update(in[hparent[i]],in[i]);
}
i=parent[hparent[i]];
}
if (root->query(in[1],in[1])==flag){
if (flag) ans+=2;
else ans-=2;
}
}
vector<int> v;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n>>q;
int a,b;
rep(x,1,n){
cin>>a>>b;
al[a].push_back(b);
al[b].push_back(a);
}
dfs(1,-1);
//cout<<ans<<endl;
parent[1]=0;
hparent[1]=1;
if (n>=2){
dfs_st(1,-1);
dfs_hld(1,-1);
}
rep(x,1,n+1) root->init(in[x],par[x]);
while (q--){
v.clear();
cin>>a;
rep(x,0,a){
cin>>b;
v.push_back(b);
}
for (auto &it:v){
if (sz(al[it])==1 && extra[it]==0){
ans++;
}
else{
ans+=depth[it]+1;
hld_query(it,true);
}
extra[it]++;
}
if (root->query(in[1],in[1])) cout<<"-1"<<endl;
else cout<<ans<<endl;
for (auto &it:v){
extra[it]--;
if (sz(al[it])==1 && extra[it]==0){
ans--;
}
else{
ans-=depth[it]+1;
hld_query(it,false);
}
}
}
}
