#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
struct segment_tree {
struct node {
int cnt[2];
node() {
memset(cnt, 0, sizeof(cnt));
}
node operator + (const node &o) {
node res;
res.cnt[0] = this->cnt[0] + o.cnt[0];
res.cnt[1] = this->cnt[1] + o.cnt[1];
return res;
}
} t[4 * N];
bool lz[4 * N];
segment_tree() {
memset(lz, false, sizeof(lz));
}
void push(int id) {
swap(t[id << 1].cnt[0], t[id << 1].cnt[1]);
lz[id << 1] ^= lz[id];
swap(t[id << 1 | 1].cnt[0], t[id << 1 | 1].cnt[1]);
lz[id << 1 | 1] ^= lz[id];
lz[id] = false;
}
void build(int id, int tl, int tr) {
if (tl == tr) {
t[id].cnt[0] = 1;
return;
}
int tm = (tl + tr) >> 1;
build(id << 1, tl, tm);
build(id << 1 | 1, tm + 1, tr);
t[id] = t[id << 1] + t[id << 1 | 1];
}
void flip(int id, int tl, int tr, int l, int r) {
if (l <= tl && tr <= r) {
swap(t[id].cnt[0], t[id].cnt[1]);
lz[id] ^= 1;
return;
}
if (lz[id]) {
push(id);
}
int tm = (tl + tr) >> 1;
if (r <= tm) {
flip(id << 1, tl, tm, l, r);
} else if (tm + 1 <= l) {
flip(id << 1 | 1, tm + 1, tr, l, r);
} else {
flip(id << 1, tl, tm, l, r);
flip(id << 1 | 1, tm + 1, tr, l, r);
}
t[id] = t[id << 1] + t[id << 1 | 1];
}
};
int n, q;
vector<int> g[N];
int sz[N], son[N], h[N], pos[N], lv[N], fa[N], deg[N];
int time_hld = 0, leaf_cnt = 0;
segment_tree st;
void pre_dfs(int u, int p) {
sz[u] = 1;
int mx = -1;
leaf_cnt += (deg[u] == 1);
for (int v : g[u]) {
if (v != p) {
fa[v] = u;
lv[v] = lv[u] + 1;
pre_dfs(v, u);
sz[u] += sz[v];
if (sz[v] > mx) {
mx = sz[v];
son[u] = v;
}
}
}
}
void decompose(int u, int p, int f) {
pos[u] = ++time_hld;
h[u] = f;
if (son[u] != 0) {
decompose(son[u], u, f);
}
for (int v : g[u]) {
if (v != p && v != son[u]) {
decompose(v, u, v);
}
}
}
void upd(int u) {
while (h[u] != 1) {
st.flip(1, 1, n, pos[h[u]], pos[u]);
u = fa[h[u]];
}
if (pos[1] < pos[u]) {
st.flip(1, 1, n, pos[1] + 1, pos[u]);
}
}
void dfs(int u, int p) {
if (deg[u] == 1) {
upd(u);
}
for (int v : g[u]) {
if (v != p) {
dfs(v, u);
}
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> q;
for (int i = 1; i <= n - 1; i++) {
int u, v;
cin >> u >> v;
g[u].emplace_back(v);
g[v].emplace_back(u);
deg[u]++;
deg[v]++;
}
pre_dfs(1, 1);
decompose(1, 1, 1);
st.build(1, 1, n);
dfs(1, 1);
while (q--) {
int l = leaf_cnt;
int d;
cin >> d;
vector<int> a(d);
for (int &x : a) {
cin >> x;
}
vector<int> redo;
for (int x : a) {
l -= (deg[x] == 1);
l++;
if (deg[x] == 1) {
upd(x);
redo.emplace_back(x);
}
deg[x]++;
upd(x);
}
for (int x : a) {
deg[x]--;
}
if (l & 1) {
cout << -1 << '\n';
} else {
cout << st.t[1].cnt[0] * 2 + st.t[1].cnt[1] + d - 2 << '\n';
}
for (int x : a) {
upd(x);
}
for (int x : redo) {
upd(x);
}
}
return 0;
}
