#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 2e5 + 5;
const int LG = 19;
int n, q;
int root;
bool is_leaf[maxn];
int eu[maxn], ev[maxn];
vector<int> g[maxn];
int leaves;
int sz[maxn], h[maxn], par[maxn];
int pos[maxn], rev[maxn], head[maxn], cur_pos;
void pre_dfs(int u, int prev) {
if ((int)g[u].size() == 1) {
++leaves;
is_leaf[u] = 1;
}
sz[u] = 1;
for (auto v : g[u]) {
if (v == prev) continue;
par[v] = u;
h[v] = h[u] + 1;
pre_dfs(v, u);
sz[u] += sz[v];
}
}
void hld(int u, int prev) {
if (!head[u]) head[u] = u;
pos[u] = ++cur_pos;
rev[cur_pos] = u;
int big_child = -1;
for (auto v : g[u]) {
if (v == prev) continue;
if (big_child == -1 || sz[big_child] < sz[v]) {
big_child = v;
}
}
if (big_child != -1) {
head[big_child] = head[u];
hld(big_child, u);
}
for (auto v : g[u]) {
if (v == prev || v == big_child) continue;
hld(v, u);
}
}
int tree[maxn << 2], lazy[maxn << 2];
void build(int ind = 1, int l = 1, int r = n) {
if (l == r) {
tree[ind] = (l > 1);
return;
}
int mid = (l + r) >> 1;
build(ind << 1, l, mid);
build(ind << 1 | 1, mid + 1, r);
tree[ind] = tree[ind << 1] + tree[ind << 1 | 1];
}
void down(int ind, int l, int r) {
tree[ind] = (r - l + 1) - tree[ind];
if (l != r) {
lazy[ind << 1] ^= lazy[ind];
lazy[ind << 1 | 1] ^= lazy[ind];
}
lazy[ind] = 0;
}
void update(int x, int y, int ind = 1, int l = 1, int r = n) {
if (lazy[ind]) {
down(ind, l, r);
}
if (l > r || l > y || r < x) return;
if (x <= l and r <= y) {
lazy[ind] = 1;
down(ind, l, r);
return;
}
int mid = (l + r) >> 1;
update(x, y, ind << 1, l, mid);
update(x, y, ind << 1 | 1, mid + 1, r);
tree[ind] = tree[ind << 1] + tree[ind << 1 | 1];
}
int get(int x, int y, int ind = 1, int l = 1, int r = n) {
if (lazy[ind]) down(ind, l, r);
if (l > y || r < x) return 0;
if (x <= l and r <= y) {
return tree[ind];
}
int mid = (l + r) >> 1;
return get(x, y, ind << 1, l, mid) + get(x, y, ind << 1 | 1, mid + 1, r);
}
void update(int u) {
while (head[u] != root) {
update(pos[head[u]], pos[u]);
u = par[head[u]];
}
update(2, pos[u]);
}
void solve() {
cin >> n >> q;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
eu[i] = u, ev[i] = v;
g[u].push_back(v);
g[v].push_back(u);
}
root = 1;
for (int i = 1; i <= n; ++i) {
if ((int)g[i].size() > 1) {
root = i;
break;
}
}
pre_dfs(root, 0);
h[root] = 1, par[root] = root;
hld(root, 0);
build();
for (int i = 1; i <= n; ++i) {
if (is_leaf[i]) {
update(i);
}
}
while(q--) {
int sz; cin >> sz;
vector<int> cur;
vector<int> prev_leaf;
for (int i = 0; i < sz; ++i) {
int p; cin >> p;
if (is_leaf[p]) {
prev_leaf.push_back(p);
}
cur.push_back(p);
update(p);
}
sort(prev_leaf.begin(), prev_leaf.end());
prev_leaf.erase(unique(prev_leaf.begin(), prev_leaf.end()), prev_leaf.end());
for (auto i:prev_leaf) {
update(i);
}
int res = leaves - (int)prev_leaf.size() + sz;
if (res & 1) {
cout << -1 << '\n';
} else {
res = n - 1 + sz + get(1, n);
cout << res << '\n';
}
for (auto i:prev_leaf) {
update(i);
}
for (auto i:cur) {
update(i);
}
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
/*
7 3
1 2
1 3
3 4
2 5
5 6
2 7
1 1
3 1 2 2
3 6 1 2
*/
