///*** Sown_Vipro ***///
/// ->TEAM SELECTION TEST<- ///
#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
#define F first
#define S second
#define pb push_back
#define pi pair<int, int>
#define pii pair<int, pair<int, int> >
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = a; i >= b; --i)
#define all(s) s.begin(), s.end()
#define szz(s) int(s.size())
const string NAME = "sown";
const int N = 1e6 + 5, MAX = 1e6, MOD = 1e9 + 7;
void maxi(int &x, int y){ if(x < y) x = y; }
void mini(int &x, int y){ if(x > y) x = y; };
void add(int &x, int y){ x += y; x += MOD * (x < 0); x -= MOD * (x >= MOD); };
int n, q, res;
int p[20][N], h[N], a[N];
vector<int> e[N];
void pre(int u){
h[u] = h[p[0][u]] + 1;
for(int v : e[u]){
if(v == p[0][u]) continue;
p[0][v] = u;
pre(v);
}
}
int lca(int u, int v){
if(h[u] < h[v]) swap(u, v);
REP(k, 18, 0){
int pu = p[k][u];
// cout << u << " " << k << " " << pu << "\n";
if(h[pu] >= h[v]) u = pu;
}
if(u == v) return u;
REP(k, 18, 0){
int pu = p[k][u], pv = p[k][v];
// cout << pu << " " << pv << "\n";
if(pu != pv){
u = pu;
v = pv;
}
}
return p[0][u];
}
int dist(int u, int v){
int w = lca(u, v);
// cout << w << "\n";
return h[u] + h[v] - 2 * h[w];
}
pair<int, int> dfs(int u, int p){
pair<int, int> c, d;
if(e[u].size() == 1){
c = {u, 0};
}
for(int v : e[u]){
if(v == p) continue;
d = dfs(v, u);
if(!c.F){
c = d;
continue;
}
if(c.S){
if(d.S){
// cout << c.S << " " << d.S << "\n";
res += dist(c.S, d.S);
c.S = d.F;
}else{
// cout << c.S << " " << d.F << "\n";
res += dist(c.S, d.F);
c.S = 0;
}
}else{
if(d.S){
// cout << c.F << " " << d.S << "\n";
res += dist(c.F, d.S);
c.F = d.F;
}else c.S = d.F;
}
}
// cout << u << " " << c.F << " " << c.S << " " << res << "\n";
return c;
}
void solve(){
cin >> n >> q;
FOR(i, 2, n){
int u, v; cin >> u >> v;
e[u].pb(v);
e[v].pb(u);
}
FOR(i, 1, q){
int s; cin >> s;
FOR(i, 1, s){
cin >> a[i];
e[a[i]].pb(i + n);
e[i + n].pb(a[i]);
// cout << a[i] << " " << i + n << "\n";
}
pre(1);
FOR(k, 1, 18) FOR(u, 1, n + s) p[k][u] = p[k - 1][p[k - 1][u]];
// cout << dist(7, 3) << "\n";
res = 0;
pair<int, int> c = dfs(1, 0);
FOR(i, 1, s){
e[a[i]].pop_back();
e[i + n].pop_back();
}
if(c.F && c.S){
res += dist(c.F, c.S);
c.F = c.S = 0;
}
if(c.F){
cout << -1 << "\n";
continue;
}
cout << res << "\n";
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
if(fopen((NAME + ".inp").c_str(), "r")){
freopen((NAME + ".inp").c_str(), "r", stdin);
// freopen((NAME + ".out").c_str(), "w", stdout);
}
int t = 1;
// cin >> t;
while(t--){
solve();
}
}
