#include <bits/stdc++.h>
using namespace std;
// #define int long long
const int INF = 1e9;
int clamp(int x) {
return min(x, INF);
}
vector<int> dp(2e5);
vector<bool> par(2e5);
vector<int> parent(2e5);
__int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
int n,q; cin >> n >> q;
vector<vector<int>> adj(n);
for (int i = 1; i < n; i++) {
int a, b; cin >> a >> b; a--; b--;
adj[a].push_back(b);
adj[b].push_back(a);
}
function<void(int,int)> dfs = [&](int v, int p) {
parent[v] = p;
bool thispar = adj[v].size() == 1;
int sum = 0;
for (int nn : adj[v]) {
if (nn != p) {
dfs(nn, v);
thispar ^= par[nn];
sum += dp[nn];
}
}
par[v] = thispar;
dp[v] = sum + (2 - par[v]);
};
dfs(0, -1);
// ONE QUERY ONLY
for (int Q = 0; Q < q; Q++) {
// auto adj_local = adj;
int m; cin >> m;
vector<int> revert(m);
vector<bool> marked(n+m);
for (int i = 0; i < m; i++) {
int x; cin >> x; x--;
revert[i] = x;
adj.push_back({x});
adj[x].push_back(n++);
marked[n-1] = 1;
while (x != -1) {
marked[x] = 1;
x = parent[x];
}
}
function<void(int,int)> dfs2 = [&](int v, int p) {
if (!marked[v]) return;
bool thispar = adj[v].size() == 1;
int sum = 0;
for (int nn : adj[v]) {
if (nn != p) {
dfs2(nn, v);
thispar ^= par[nn];
sum += dp[nn];
}
}
par[v] = thispar;
dp[v] = sum + (2 - par[v]);
};
dfs2(0, -1);
if (par[0]) cout << -1 << "\n";
else cout << dp[0] - 2 + par[0] << "\n";
n -= m;
adj.resize(n);
for (int e : revert) adj[e].pop_back();
dfs2(0, -1);
}
return 0;
}
