#include <bits/stdc++.h>
#include <ext/random>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#define pb push_back
#define ppb pop_back
#define fr first
#define sc second
#define all(v) v.begin(), v.end()
#define vektor vector
using namespace std;
using namespace __gnu_pbds;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
constexpr ull Mod = 1e9 + 7;
constexpr ull Mod2 = 1 + 7 * 17 * (1 << 23);
constexpr ull sqr = 320;
constexpr ld eps = 1e-9;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll random(ll l, ll r) {if(l <= r) return uniform_int_distribution <ll> (l, r)(rng); return -1;}
int st[400005], lazy[400005];
void update111(int idx, int l, int r, int u, int v){
if(lazy[idx] == 1){
st[idx] = (r - l + 1) - st[idx];
if(l != r){
lazy[idx << 1] ^= 1;
lazy[idx << 1 | 1] ^= 1;
}
lazy[idx] = 0;
}
if(v < l || r < u) return;
if(u <= l && r <= v){
st[idx] = (r - l + 1) - st[idx];
if(l != r){
lazy[idx << 1] ^= 1;
lazy[idx << 1 | 1] ^= 1;
}
return;
}
int mid = (l + r) >> 1;
update111(idx << 1, l, mid, u, v);
update111(idx << 1 | 1, mid + 1, r, u, v);
st[idx] = st[idx << 1] + st[idx << 1 | 1];
}
int query111(int idx, int l, int r, int u, int v){
if(lazy[idx] == 1){
st[idx] = (r - l + 1) - st[idx];
if(l != r){
lazy[idx << 1] ^= 1;
lazy[idx << 1 | 1] ^= 1;
}
lazy[idx] = 0;
}
if(v < l || r < u) return 0;
if(u <= l && r <= v) return st[idx] + (r - l + 1 - st[idx]) * 2;
int mid = (l + r) >> 1;
return query111(idx << 1, l, mid, u, v) + query111(idx << 1 | 1, mid + 1, r, u, v);
}
void update(int l, int r){update111(1, 1, 100000, l, r);}
int query(int l, int r){return query111(1, 1, 100000, l, r);}
int n;
vector <int> graph[100005];
int h[100005], subtr[100005], parent[100005];
int heavy_p[100005];
int id[100005];
void dfs111(int node, int pr){
h[node] = h[pr] + 1;
subtr[node] = 1;
parent[node] = pr;
for(auto& x : graph[node]){
if(x == pr) continue;
dfs111(x, node);
subtr[node] += subtr[x];
}
}
int timer = 0;
void dfs222(int node, int pr){
id[node] = ++ timer;
pair <int, int> mx = {0, 0};
for(auto& x : graph[node]){
if(x == pr) continue;
mx = max(mx, {subtr[x], x});
}
heavy_p[mx.sc] = heavy_p[node];
if(mx.fr) dfs222(mx.sc, node);
for(auto& x : graph[node]){
if(x == mx.sc || x == pr) continue;
heavy_p[x] = x;
dfs222(x, node);
}
}
void preprocess(){
memset(st, 0, sizeof(st));
memset(lazy, 0, sizeof(lazy));
heavy_p[1] = 1;
dfs111(1, 0);
dfs222(1, 0);
}
void flip(int u){
while(u){
int next = (h[heavy_p[u]] >= 1) ? heavy_p[u] : 1;
update(id[next], id[u]);
u = parent[next];
}
}
void solve(){
int Q;
cin >> n >> Q;
int leafcnt = 0;
int cnt[n + 1];
memset(cnt, 0, sizeof(cnt));
for(int i = 1; i < n; i ++){
int u, v;
cin >> u >> v;
graph[u].pb(v);
graph[v].pb(u);
}
preprocess();
for(int i = 1; i <= n; i ++){
if(graph[i].size() == 1) flip(i), leafcnt ++;
}
while(Q --){
int k, curleaf = 0;
cin >> k;
vector <int> cpr, flipped;
for(int i = 1; i <= k; ++ i){
int x;
cin >> x;
cnt[x] ++;
cpr.pb(x);
}
sort(all(cpr));
cpr.resize(unique(all(cpr)) - cpr.begin());
for(auto& x : cpr) curleaf -= (graph[x].size() == 1) ? 1 : 0;
if((leafcnt + curleaf + k) & 1){
for(auto& x : cpr) cnt[x] = 0;
cout << "-1\n";
continue;
}
for(auto& x : cpr){
if(graph[x].size() == 1 && !(cnt[x] & 1)){
flip(x);
flipped.pb(x);
continue;
}
if(graph[x].size() != 1 && (cnt[x] & 1)){
flip(x);
flipped.pb(x);
}
}
cout << st[1] + (n - st[1] - 1) * 2 + k << "\n";
for(auto& x : cpr) cnt[x] = 0;
for(auto& x : flipped) flip(x);
}
}
main(){
// cout << 1; return 0;
ios_base::sync_with_stdio(false);
cin.tie(NULL);
if(fopen("Topic.inp", "r")){
freopen("Topic.inp", "r", stdin);
freopen("Topic.out", "w", stdout);
}
int t = 1;
// cin >> t;
while(t --){
solve();
cout << "\n";
}
}
// Whose eyes are those eyes?
