#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
inline void debugMode() {
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif // ONLINE_JUDGE
}
const int N = 1e5 + 10;
vector<int> v[N];
int n, q;
int c[N], add[N], f[N], p[N], tin[N], tout[N], tt, st[N], sz[N], t[4 * N][2], upd[4 * N], rev[N], k;
int res, root;
void trace(int x, int p) {
tin[x] = ++tt;
int big = -1;
for (auto to : v[x]) {
if (to == p) {
continue;
}
if (big == -1 || sz[to] > sz[big]) {
big = to;
}
}
// cout << x << " -> " << big << "\n";
if (big != -1) {
st[big] = st[x];
trace(big, x);
}
for (auto to : v[x]) {
if (to == p || to == big) {
continue;
}
st[to] = to;
trace(to, x);
}
tout[x] = tt;
}
void build(int x, int tl, int tr) {
if (tl == tr) {
t[x][0] = 1;
return;
}
int tm = (tl + tr) / 2;
build(2 * x, tl, tm);
build(2 * x + 1, tm + 1, tr);
t[x][0] = t[2 * x][0] + t[2 * x + 1][0];
}
void push(int x) {
if (upd[x] == 0) {
return;
}
upd[2 * x] ^= 1;
upd[2 * x + 1] ^= 1;
upd[x] = 0;
swap(t[2 * x][0], t[2 * x][1]);
swap(t[2 * x + 1][0], t[2 * x + 1][1]);
}
void update(int x, int tl, int tr, int l, int r) {
if (r < tl || l > tr)
return;
if (l <= tl && r >= tr) {
upd[x] ^= 1;
res -= t[x][1];
swap(t[x][0], t[x][1]);
res += t[x][1];
return;
}
int tm = (tl + tr) / 2;
push(x);
update(2 * x, tl, tm, l, r);
update(2 * x + 1, tm + 1, tr, l, r);
t[x][0] = t[2 * x][0] + t[2 * x + 1][0];
t[x][1] = t[2 * x][1] + t[2 * x + 1][1];
}
void update(int x) {
if (x == 0)
return;
// cout << "update " << st[x] << " " << x << "\n";
update(1, 1, tt, tin[st[x]], tin[x]);
update(p[st[x]]);
// cout << "new: " << res << "\n";
}
void dfs(int x, int p) {
::p[x] = p;
c[x] = (v[x].size() == 1);
sz[x] = 1;
k += c[x];
for (auto to : v[x]) {
if (to == p)
continue;
dfs(to, x);
sz[x] += sz[to];
c[x] += c[to];
}
// res += (x == root ? 0 : c[x] ^ 1);
}
void solve() {
cin >> n >> q;
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
v[a].push_back(b);
v[b].push_back(a);
}
for (int i = 1; i <= n; i++) {
if (v[i].size() > 1) {
root = i;
break;
}
}
// cout << root << "\n";
dfs(root, 0);
st[root] = root;
trace(root, 0);
build(1, 1, tt);
for (int i = 1; i <= n; i++) {
if (c[i] % 2 == 0) {
// cout << "i: " << c[i] << "\n";
update(1, 1, tt, tin[i], tin[i]);
}
}
// cout << res << "\n";
// cout << "kerima\n";
// return;
while (q--) {
int d;
cin >> d;
vector<int> g(d);
for (auto &i : g) {
cin >> i;
k++;
f[i]++;
if (v[i].size() + f[i] == 2) {
k--;
continue;
}
update(i);
}
// cout << "Res: " << res << "\n";
cout << (k % 2 ? -1 : res + n - 2 + d) << "\n";
for (auto &i : g) {
f[i]--;
k--;
if (v[i].size() + f[i] == 1) {
k++;
continue;
}
update(i);
}
}
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
debugMode();
int $ = 1;
// cin >> $;
while ($--) {
solve();
}
}
