/*************************************
* author: marvinthang *
* created: 29.04.2024 17:01:01 *
*************************************/
#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define left ___left
#define right ___right
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define MASK(i) (1LL << (i))
#define BIT(x, i) ((x) >> (i) & 1)
#define __builtin_popcount __builtin_popcountll
#define ALL(v) (v).begin(), (v).end()
#define REP(i, n) for (int i = 0, _n = (n); i < _n; ++i)
#define REPD(i, n) for (int i = (n); i-- > 0; )
#define FOR(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define FORD(i, b, a) for (int i = (b), _a = (a); --i >= _a; )
#define FORE(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORDE(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define scan_op(...) istream & operator >> (istream &in, __VA_ARGS__ &u)
#define print_op(...) ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
#include "debug.h"
#else
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
#define DB(...) 23
#define db(...) 23
#define debug(...) 23
#endif
template <class U, class V> scan_op(pair <U, V>) { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>) { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>) { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")"; else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
// end of template
const int LOG = 17;
void process(void) {
int n, q; cin >> n >> q;
vector <vector <int>> adj(n);
REP(i, n - 1) {
int u, v; cin >> u >> v; --u; --v;
adj[u].push_back(v);
adj[v].push_back(u);
}
vector <int> parity(n), depth(n), tin(n), tout(n), pref_even(n);
vector <array <int, LOG>> anc(n);
vector <bool> is_leaf(n);
auto dfs = [&] (auto &&dfs, int u, int par) -> void {
static int t = 0;
tin[u] = ++t;
anc[u][0] = par;
FOR(i, 1, LOG) anc[u][i] = anc[anc[u][i - 1]][i - 1];
depth[u] = depth[par] + 1;
is_leaf[u] = (int) adj[u].size() == 1;
parity[u] = is_leaf[u];
for (int v: adj[u]) if (v != par) {
dfs(dfs, v, u);
parity[u] ^= parity[v];
}
tout[u] = t;
};
dfs(dfs, 0, 0);
auto dfs2 = [&] (auto &&dfs2, int u) -> void {
pref_even[u] += parity[u];
for (int v: adj[u]) if (v != anc[u][0]) {
pref_even[v] = pref_even[u];
dfs2(dfs2, v);
}
};
dfs2(dfs2, 0);
auto __lca = [&] (int u, int v) {
if (depth[u] < depth[v]) swap(u, v);
REPD(i, LOG) if (depth[anc[u][i]] >= depth[v]) u = anc[u][i];
if (u == v) return u;
REPD(i, LOG) if (anc[u][i] != anc[v][i]) {
u = anc[u][i];
v = anc[v][i];
}
return anc[u][0];
};
int init = n - 1;
FOR(i, 1, n) init += !parity[i];
vector <int> cur_parity(n);
auto cmp = [&] (int u, int v) { return tin[u] < tin[v]; };
REP(i, n) adj[i].clear();
while (q--) {
int d; cin >> d;
vector <int> lst(d); cin >> lst;
int res = init + d;
for (int &u: lst) {
--u;
cur_parity[u] ^= 1;
}
sort(ALL(lst), cmp);
lst.erase(unique(ALL(lst)), lst.end());
for (int u: lst) if (is_leaf[u]) cur_parity[u] ^= 1;
REP(i, (int) lst.size() - 1) lst.push_back(__lca(lst[i], lst[i + 1]));
lst.push_back(0);
sort(ALL(lst), cmp);
lst.erase(unique(ALL(lst)), lst.end());
stack <int> st;
st.push(lst[0]);
FOR(i, 1, lst.size()) {
int u = lst[i];
while (!st.empty() && (tin[u] < tin[st.top()] || tin[u] > tout[st.top()])) st.pop();
adj[st.top()].push_back(u);
st.push(u);
}
auto dfs = [&] (auto &&dfs, int u) -> void {
for (int v: adj[u]) {
dfs(dfs, v);
if (cur_parity[v]) {
res += 2 * (pref_even[v] - pref_even[u]) - (depth[v] - depth[u]);
}
cur_parity[u] ^= cur_parity[v];
}
};
dfs(dfs, 0);
cout << (cur_parity[0] ^ parity[0] ? -1 : res) << '\n';
for (int u: lst) {
cur_parity[u] = 0;
adj[u].clear();
}
}
}
int main(void) {
ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
file("cleaning");
// int t; cin >> t; while (t--)
process();
// cerr << "Time elapsed: " << TIME << " s.\n";
return (0^0);
}
