#include<bits/stdc++.h>
using namespace std;
#define FOR(i , a, b) for(int i = a; i <= b ; i++)
#define REP(i , a, b) for(int i = b; i >= a ; i--)
#define ALL(v) v.begin() , v.end()
#define F first
#define pb push_back
#define S second
bool maximize(int& x,int y){
if(x < y){
x = y;
return 1;
}
return 0;
}
bool maximizell(long long & x,long long y){
if(x < y){
x = y;
return 1;
}
return 0;
}
bool minimize(int& x,int y){
if(x > y){
x = y;
return 1;
}
return 0;
}
bool minimizell(long long & x,long long y){
if(x > y){
x = y;
return 1;
}
return 0;
}
const int maxN = 1e5 + 999;
int n , q, sz[maxN];
vector<int> event[maxN];
vector<int> e[maxN];
pair<int ,int > Edge[maxN];
namespace sub1{
int vis[maxN];
bool check(){
FOR(i, 2, n){
int u = Edge[i].F , v = Edge[i].S;
if(u != 1 && v != 1)return 0;
}
return 1;
}
void solve(){
int leaves = n - 1;
int cost = n - 1;
FOR(i, 1, q){
for(auto x : event[i]){
if(vis[x] == 0)vis[x] = 1;
else ++leaves;
++cost;
}
if( (leaves % 2 ) == 1){
cout << -1 << '\n';
}else{
cout << cost << '\n';
}
for(auto x : event[i]){
if(vis[x] == 1)vis[x] = 0;
else --leaves;
--cost;
}
}
}
}
namespace sub2{
int leaf[maxN] ,cnt, mark[maxN];
void pre(int u ,int p){
leaf[u] = 0;
// cout << u << " ";
for(auto x :e[u]){
// cout << x<< " ";
if(x == p)continue;
pre(x, u);
}
// cout << u << " " ;
if(e[u].size() == 1){
leaf[u] = 1;
++cnt;
}
}
int ans = 0;
vector<int> dp[maxN];
void dfs(int u ,int p){
for(auto x : e[u]){
if(x == p)continue;
dfs(x, u);
for(auto kk : dp[x]){
dp[u].pb(kk + 1);
}
}
while(dp[u].size() >= 3){
int x = dp[u].back();
dp[u].pop_back();
int y = dp[u].back();
ans += x + y;
dp[u].pop_back();
}
if(p == 0){
while(dp[u].size()){
int x = dp[u].back();
dp[u].pop_back();
int y = dp[u].back();
ans += x + y;
dp[u].pop_back();
}
}
}
void solve(){
int root = -1;
FOR(i, 1, n){
if(e[i].size() >= 2)root = i;
if(root != -1)break;
}
// cout << root;
FOR(i, 1, q){
ans = 0;
cnt = 0;
pre(root, 0);
for(auto x : event[i]){
if(leaf[x] == 1 && mark[x] == 0)mark[x] = 1;
else if(leaf[x] == 0 && mark[x] == 1)++cnt;
else if(leaf[x] == 0)++cnt;
leaf[x] = 0;
dp[x].pb(1);
}
// cout << cnt << " ";
if( (cnt % 2) == 1)cout << -1 << '\n';
else{
FOR(u, 1, n)if(leaf[u])dp[u].pb(0);
dfs(root , 0);
cout <<ans << '\n';
}
FOR(u, 1, n){
dp[u].clear();
mark[u] = 0;
}
}
// cout << cnt;
}
}
void solve(){
cin >> n >> q;
FOR(i, 2, n){
int u ,v;
cin >> u >> v;
e[u].pb(v);
e[v].pb(u);
Edge[i] = {u , v};
}
FOR(i, 1 ,q){
cin >> sz[i];
FOR(x ,1 ,sz[i]){
int u; cin >> u;
event[i].pb(u);
}
}
if(sub1::check())return sub1::solve();
return sub2::solve();
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
// freopen("crt.inp", "r" , stdin);
// freopen("crt.out", "w" ,stdout);
int tc = 1;
while(tc--)solve();
}
