#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 17;
int n, q, r, c[N];
int ti, m, in[N], out[N], lg, p[N][21], d[N];
long long z1, z2;
vector <int> adj[N];
vector <pair <int, int>> leaf;
void dfs (int u, int pr)
{
in[u] = ++ti, p[u][0] = pr, d[u] = d[pr] + 1;
for (int i = 1; i <= lg; ++i)
{
p[u][i] = p[p[u][i - 1]][i - 1];
}
for (int v: adj[u])
{
if (v != pr)
{
dfs (v, u);
}
}
if (adj[u].size() == 1)
{
leaf.push_back ({in[u], u});
++m;
}
out[u] = ti;
}
int lca (int u, int v)
{
if (d[u] < d[v])
{
swap (u, v);
}
for (int i = lg; i >= 0; --i)
{
if (d[p[u][i]] >= d[v])
{
u = p[u][i];
}
}
if (u == v)
{
return u;
}
for (int i = lg; i >= 0; --i)
{
if (p[u][i] != p[v][i])
{
u = p[u][i], v = p[v][i];
}
}
return p[u][0];
}
int dist (int u, int v)
{
return d[u] + d[v] - 2 * d[lca (u, v)];
}
void sub1()
{
int ans = 0;
for (int i = 1; i <= n; ++i)
{
if (i != r)
{
++ans;
}
}
while (q--)
{
int sz, z = m, _ = ans;
cin >> sz;
while (sz--)
{
int x;
cin >> x;
if (x == r)
{
++z, ++ans;
continue;
}
++c[x], z += (c[x] > 1);
}
for (int i = 1; i <= n; ++i)
{
if (c[i] & 1)
{
ans += c[i];
}
else
{
ans += (c[i] > 0) * (c[i] + 1);
}
c[i] = 0;
}
if (z & 1)
{
cout << "-1\n";
}
else
{
cout << ans << "\n";
}
ans = _;
}
}
void sub2()
{
while (q--)
{
int sz;
vector <int> vt;
cin >> sz;
for (int i = 1, x; i <= sz; ++i)
{
cin >> x;
adj[x].push_back(n + i);
adj[n + i].push_back(x);
vt.push_back(x);
}
m = ti = 0, lg = __lg(n + sz);
dfs (r, 0);
if (m & 1)
{
cout << "-1\n";
}
else
{
sort (leaf.begin(), leaf.end());
z2 = dist (leaf[0].second, leaf[m - 1].second);
for (int i = 1; i < m; i += 2)
{
z1 += dist (leaf[i].second, leaf[i - 1].second);
}
for (int i = 2; i < m - 1; i += 2)
{
z2 += dist (leaf[i].second, leaf[i - 1].second);
}
cout << min (z1, z2) << "\n";
}
leaf.clear();
for (int x: vt)
{
adj[x].pop_back();
}
for (int i = 1; i <= sz; ++i)
{
adj[n + i].clear();
}
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> q;
for (int i = 1, u, v; i < n; ++i)
{
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; ++i)
{
if (adj[i].size() > 1)
{
r = i;
continue;
}
++m;
}
if (m >= n - 1)
{
sub1();
return 0;
}
sub2();
}
