//#pragma GCC optimize("O3,unroll-loops")
//#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#include<bits/stdc++.h>
#define ll long long
#define F first
#define S second
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define all(x) x.begin(), x.end()
const int mod = 1e9 + 7;
const int N = 300001;
using namespace std;
ll n, q, m, a, b, c, d[N], cntleaves, p[N], sz[N], timer, cen, ans;
vector <ll> g[N], v;
pair <ll, ll> e[N];
void pre_calc (ll v, ll pr){
sz[v] = 1;
for (auto i: g[v]){
if (i != pr){
pre_calc (i, v);
sz[v] += sz[i];
}
}
}
ll find_c (ll v, ll pr){
for (auto i: g[v]){
if (i != pr && sz[i] > n / 2){
return find_c (i, v);
}
}
return v;
}
void dfs (ll v, ll pr, ll dep){
if (g[v].size() == 1){
ans += dep;
}
for (auto i: g[v]){
if (i != pr){
dfs (i, v, dep + 1);
}
}
}
signed main (){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> q;
for (int i = 1; i < n; i++){
cin >> e[i].F >> e[i].S;
a = e[i].F, b = e[i].S;
g[a].pb (b);
g[b].pb (a);
}
for (int z = 1; z <= q; z++){
cin >> m;
ans = 0;
timer = n;
for (int j = 1; j <= m; j++){
cin >> p[j];
++timer;
g[p[j]].pb (timer);
g[timer].pb (p[j]);
}
cntleaves = 0;
for (int i = 1; i <= timer; i++){
if (g[i].size() == 1){
cntleaves++;
}
}
pre_calc (1, 1);
cen = find_c (1, 1);
// cout << cen << ' ';
for (auto i: g[cen]){
dfs (i, cen, 1);
}
// cout << '\n';
if (cntleaves % 2){
ans = -1;
}
cout << ans << '\n';
for (int i = 1; i <= timer; i++){
g[i].clear();
}
for (int i = 1; i < n; i++){
a = e[i].F, b = e[i].S;
g[a].pb (b);
g[b].pb (a);
}
}
}
