#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;
const int MAX = 100006;
long long tree1[262144]; /// mod 2
long long lazy1[262144];
void propagate1(int i, int b, int e) {
if (!lazy1[i]) return;
if (b != e) {
lazy1[i * 2 + 1] += lazy1[i];
lazy1[i * 2 + 2] += lazy1[i];
}
if (lazy1[i] % 2) tree1[i] = (e - b + 1) - tree1[i];
lazy1[i] = 0;
}
long long update1(int i, int b, int e, int l, int r, int v) {
propagate1(i, b, e);
if (r < b || e < l) return tree1[i];
if (l <= b && e <= r) {
lazy1[i] += v;
propagate1(i, b, e);
return tree1[i];
}
int m = (b + e) / 2;
return tree1[i] = update1(i * 2 + 1, b, m, l, r, v) + update1(i * 2 + 2, m + 1, e, l, r, v);
}
long long tree2[262144]; /// more than 0
long long lazy2[262144];
void update2(int i, int b, int e, int l, int r, int v) {
if (r < b || e < l) return;
int m = (b + e) / 2;
if (l <= b && e <= r) lazy2[i] += v;
else update2(i * 2 + 1, b, m, l, r, v), update2(i * 2 + 2, m + 1, e, l, r, v);
if (lazy2[i]) tree2[i] = e - b + 1;
else if (b == e) tree2[i] = 0;
else tree2[i] = tree2[i * 2 + 1] + tree2[i * 2 + 2];
}
void update(int l, int r, int v) {
update1(0, 0, 131071, l, r, v);
update2(0, 0, 131071, l, r, v);
}
int sz[MAX], in[MAX], top[MAX], t;
int n, q, d, childs[MAX], depth[MAX], par[MAX];
bool alreadyLeaf[MAX];
vector<int> adj[MAX], c[MAX];
int dfs_sz(int x) {
sz[x] = 1;
for (auto &i: c[x]) {
sz[x] += dfs_sz(i);
if (sz[i] > sz[c[x][0]]) swap(i, c[x][0]);
}
return sz[x];
}
void dfs_hld(int x) {
in[x] = t++;
for (auto &i: c[x]) {
top[i] = (i == c[x][0] ? top[x] : i);
dfs_hld(i);
}
}
void dfs(int x, int prev = -1) {
par[x] = prev;
for (auto &i: adj[x]) if (i != prev) {
depth[i] = depth[x] + 1;
dfs(i, x);
c[x].push_back(i);
}
}
void update_hld(int x, int y, int v) {
while (top[x] != top[y]) {
if (depth[top[x]] < depth[top[y]]) swap(x, y);
update(in[top[x]], in[x], v);
x = par[top[x]];
}
if (in[x] > in[y]) swap(x, y);
update(in[x], in[y], v);
}
int main() {
scanf("%d%d", &n, &q);
for (int i = 0; i < n - 1; i++) {
int a, b;
scanf("%d%d", &a, &b);
a--, b--;
adj[a].push_back(b);
adj[b].push_back(a);
}
dfs(0);
dfs_sz(0);
dfs_hld(0);
int r = 0;
for (int i = 0; i < n; i++) {
if (i == 0 && (int)c[0].size() != 1) continue;
if (i != 0 && !c[i].empty()) continue;
update_hld(0, i, 1);
alreadyLeaf[i] = true;
r++;
}
int _or = r;
while (q--) {
r = _or;
scanf("%d", &d);
vector<int> x;
for (int i = 0; i < d; i++) {
int t;
scanf("%d", &t); t--;
x.push_back(t);
childs[t]++;
if (alreadyLeaf[t] && childs[t] == 1) continue;
update_hld(0, t, 1), r++;
}
if (r % 2) {
puts("-1");
goto next;
}
{
propagate1(0, 0, 131071);
long long first = tree1[0];
long long second = tree2[0];
if (r > 0) second--;
printf("%lld\n", 2 * second - first + d);
}
next:
for (int i = (int)x.size() - 1; i >= 0; i--) {
childs[x[i]]--;
if (alreadyLeaf[x[i]] && !childs[x[i]]) continue;
update_hld(0, x[i], -1);
}
}
}
