#include <bits/stdc++.h>
using namespace std;
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define pb push_back
#define sp " "
#define endl "\n"
#define pii pair<int, int>
#define st first
#define nd second
#define N 200005
vector<int> adj[N];
int val[N], par[N], deg[N];
int ans;
int dfs(int node, int root)
{
int flag = 0;
par[node] = root;
for (auto i : adj[node])
{
if (i != root) flag ^= dfs(i, node);
}
if (adj[node].size() == 1) flag ^= 1;
val[node] = flag;
if (flag == 0) val[node] = 2;
ans += val[node];
//cout<<node<<sp<<flag<<endl;
return flag;
}
int32_t main()
{
fastio();
int n, q;
cin>>n>>q;
for (int i = 1; i < n; i++)
{
int u, v;
cin>>u>>v;
adj[u].pb(v);
adj[v].pb(u);
}
while(q--)
{
int d;
cin>>d;
ans = 0;
vector<int> v(d, 0);
for (int i = 0; i < d; i++)
{
int node;
cin>>node;
adj[n + i + 1].pb(node);
adj[node].pb(n + i + 1);
v[i] = node;
}
int flag = dfs(1, 0);
ans -= val[1];
if (flag) cout<<-1<<endl;
else cout<<ans<<endl;
for (int i = 0; i < d; i++)
{
int node = v[i];
adj[node].pop_back();
adj[n + i + 1].pop_back();
}
}
cerr<<"time taken : "<<(float)clock() / CLOCKS_PER_SEC<<" seconds\n";
}
