#include <bits/stdc++.h>
using namespace std;
#define int ll
#define endl '\n' //comment for interactive
#define fast_io ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define pb push_back
#define re resize
#define ff first
#define ss second
#define all(x) (x).begin(), (x).end()
#define all1(x) (x).begin()+1, (x).end()
#define loop(i, n) for(int i = 0; i < n; i++)
#define loop1(i, n) for(int i = 1; i <= n; i++)
#define print(x) cout << #x << ": " << x << endl << flush
typedef long long ll;
typedef vector<int> vi;
typedef array<int, 2> ii;
typedef array<int, 3> ti;
typedef vector<ii> vii;
typedef vector<ti> vti;
typedef vector<vi> vvi;
typedef priority_queue<int> pq;
template<class T> bool ckmin(T&a, T b) { bool B = a > b; a = min(a, b); return B; }
template<class T> bool ckmax(T&a, T b) { bool B = a < b; a = max(a, b); return B; }
const int inf = 1e17;
const int maxn = 2e5+5;
vi adj[maxn];
void solve() {
int n, q;
cin >> n >> q;
loop1(i, n-1) {
int u, v;
cin >> u >> v;
adj[u].pb(v);
adj[v].pb(u);
}
while(q--) {
int d; cin >> d;
vi a(d+1);
loop1(i, d) cin >> a[i];
loop1(i, d) {
adj[a[i]].pb(n+i);
adj[n+i].pb(a[i]);
}
vi lv(n+d+1);
int res = 0;
auto dfs = [&] (int u, int p, auto dfs) -> void {
for(auto v : adj[u]) if(v != p) {
dfs(v, u, dfs);
lv[u] += lv[v];
}
if(adj[u].size() == 1) lv[u] += 1;
if(u != p) res += 1 + !(lv[u] & 1);
};
dfs(1, 1, dfs);
if(lv[1] & 1) cout << -1 << endl;
else cout << res << endl;
loop1(i, d) {
adj[a[i]].pop_back();
adj[n+i].pop_back();
}
}
}
signed main() {
fast_io;
int t = 1; //cin >> t;
while(t--)
solve();
return 0;
}
