#include<bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
pii combine(pii a, pii b){
return {a.first +b.first, a.second+b.second};
}
struct SegTree{
vector<pii> tr;
vector<int> d;
int sz= 1;
void init(int len){
while(sz<len){
sz*=2;
}
tr.resize(2*sz, {0, 0});
d.resize(2*sz, 0);
}
void build(vector<int>&v, int lt, int rt, int t){
if(lt>=v.size()){
tr[t] ={0, 0};
}
if(lt==rt){
if(v[lt] ==0){
tr[t] = {1, 0};
}
else{
tr[t] = {0, 1};
}
}
else{
int mid = (lt+rt)/2;
build(v, lt, mid, t*2);
build(v, mid+1, rt, t*2+1);
tr[t] = combine(tr[t*2], tr[t*2+1]);
}
}
void push(int id){
if(d[id]!=0){
swap(tr[id*2].first, tr[id*2].second);
swap(tr[id*2+1].first, tr[id*2+1].second);
d[id] =0;
d[id*2] ^=1;
d[id*2+1] ^=1;
}
}
void flip(int l, int r, int lt, int rt, int t){
if(l<= lt && rt<=r){
d[t]^=1;
swap(tr[t].first, tr[t].second);
}
else if(rt<l || r<lt){
//cout<<"done "<<endl;
return;
}
else{
push(t);
int mid =(lt+rt)/2;
flip(l, r, lt, mid, t*2);
flip(l, r, mid+1, rt, t*2+1);
tr[t] = combine(tr[t*2], tr[t*2+1]);
}
}
pii get(int l, int r, int lt, int rt, int t){
pii res;
if(rt<l || r<lt){
res= {0, 0};
}
else if(l<= lt && rt<=r){
res= tr[t];
}
else{
push(t);
int mid = (lt+rt)/2;
res= combine(get(l, r, lt, mid, t*2), get(l, r, mid+1, rt, t*2+1));
}
return res;
}
pii change(int l, int r){
//cout<<"changing on "<<l<<" "<<r<<endl;
flip(l, r, 0, sz-1, 1);
return get(l, r, 0, sz-1, 1);
}
};
struct HLD{
SegTree seg;
vector<int> parent, heavy, head, pos, depth, pairdeg;
vector<vector<int>> adj;
int cur_pos =0;
int root =0;
HLD(int sz, vector<int>& parities, vector<vector<int>> ad, int r){
root =r;
parent.resize(sz);
heavy.resize(sz);
head.resize(sz);
pos.resize(sz);
adj.resize(sz);
depth.resize(sz);
pairdeg.resize(sz);
adj =ad;
dfs(root, -1, 0);
decompose(root, root);
seg.init(sz);
for(int i = 0; i<sz; i++){
pairdeg[pos[i]] = parities[i];
}
seg.build(pairdeg, 0, seg.sz-1, 1);
}
int dfs(int u, int a, int dp){
depth[u] =dp;
parent[u] = a;
int sz= 1;
int id= -1, maxsz= 0;
for(auto v: adj[u]){
if(v!=a){
int res= dfs(v, u, dp+1);
if(res>maxsz){
id = v;
maxsz =res;
}
sz+=res;
}
}
heavy[u] = id;
return sz;
}
void decompose(int u, int h){
head[u] = h;
pos[u] = cur_pos++;
if(heavy[u]!=-1){
decompose(heavy[u], h);
}
for(auto v: adj[u]){
if(v!=heavy[u] && v!=parent[u]){
decompose(v, v);
}
}
};
pii change_upwards(int u){
pii res ={0, 0};
while(head[u] != root){
//cout<<"c "<<head[u]<<" "<<u<<endl;
res = combine(res, seg.change(pos[head[u]], pos[u]));
u = parent[head[u]];
}
//cout<<"c "<<root <<" "<<u<<endl;
res = combine(res, seg.change(pos[root], pos[u]));
//cout<<"cres "<<res.first<<" "<<res.second<<endl;
return res;
}
};
const int MAX_N = 100000;
vector<vector<int>> adj;
vector<int> parity;
vector<int> cost = {2, 1};
int total_cost= 0;
int count_leaves(int u, int a){
int s= 0;
for(auto v: adj[u]){
if(v!=a){
s+=count_leaves(v, u);
}
}
if(s==0){
s=1;
}
total_cost+= cost[s%2];
//cout<<u+1<<" "<<s<<endl;
parity[u] = s%2;
return s;
}
signed main(){
cin.tie(NULL);
ios_base::sync_with_stdio(false);
int n, k;
cin>>n>>k;
adj.resize(n);
parity.resize(n);
int node = 0;
int deg= 0;
for(int i = 0; i<n-1; i++){
int a, b;
cin>>a>>b;
a--;b--;
adj[a].push_back(b);
adj[b].push_back(a);
if(adj[a].size()>deg){
node =a;
deg = adj[a].size();
}
if(adj[b].size()>deg){
node =b;
deg = adj[b].size();
}
}
int r= count_leaves(node, -1);
HLD hld(n, parity, adj, node);
//pii v= hld.seg.get(0, 0, 0, hld.seg.sz-1, 1);
//cout<<v.first<<" "<<v.second<<endl;
for(int i = 0; i<k; i++){
int d;
cin>>d;
vector<int> pos(d);
for(int i = 0; i<d; i++){
cin>>pos[i];
pos[i]--;
}
for(auto e: pos){
adj[e].push_back(-1);
if(adj[e].size()>2){
pii new_val =hld.change_upwards(e);
total_cost -= new_val.second * cost[0] + new_val.first * cost[1];
total_cost += new_val.first * cost[0] + new_val.second * cost[1];
}
}
pii v= hld.seg.get(0, 0, 0, hld.seg.sz-1, 1);
//cout<<v.first<<" "<<v.second<<endl;
if(hld.seg.get(0, 0, 0, hld.seg.sz-1, 1) != pair<int, int>({1, 0})){
cout<<-1<<endl;
}
else{
cout<<total_cost-2 +d<<endl;
}
for(auto e: pos){
if(adj[e].size()>2){
pii new_val =hld.change_upwards(e);
total_cost -= new_val.second * cost[0] + new_val.first * cost[1];
total_cost += new_val.first * cost[0] + new_val.second * cost[1];
}
adj[e].pop_back();
}
//cout<<"baseline: "<<total_cost-2<<endl;
}
}
