#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define pb push_back
#define fi first
#define se second
using namespace std;
typedef long long ll;
const int MAXN = 200005;
int n, q, ans, sz;
int u[MAXN], v[MAXN], dp[MAXN];
vector < int > g[MAXN], adj[MAXN];
void dfs(int v, int p){
if(g[v].size() == 1) dp[v] = 1;
else dp[v] = 0;
for(int u : g[v]){
if(u == p) continue;
dfs(u, v);
}
for(int u : g[v]){
if(u == p) continue;
dp[v] += dp[u];
}
if(v == 1) dp[v] = 0;
while(dp[v] > 2) dp[v] -= 2;
ans += dp[v];
// cout << "vertex: " << v << " dp: " << dp[v] << '\n';
}
signed main(){
cin >> n >> q, sz = n;
for(int i = 1; i < n; i++) cin >> u[i] >> v[i], adj[u[i]].pb(v[i]), adj[v[i]].pb(u[i]);
while(q--){
for(int i = 1; i <= sz; i++) g[i].clear();
for(int i = 1; i <= n; i++) g[i] = adj[i];
int d, x, cnt = 0; cin >> d, sz = n, ans = 0;
while(d--) cin >> x, sz++, g[x].pb(sz), g[sz].pb(x);
for(int i = 1; i <= sz; i++)
if(g[i].size() == 1)
cnt++;
if(cnt % 2){
cout << "-1\n";
continue;
}
ans = 0, dfs(1, 1);
cout << ans << '\n';
}
}
/*
g++ cleaning.cpp -o program.exe
program.exe
7 3
1 2
2 4
4 5
5 6
5 7
3 4
1 4
2 2 4
1 1
*/
