#include <bits/stdc++.h>
using i64 = long long;
using namespace std;
struct SegmentTree {
int n;
vector<int> t, lz;
SegmentTree(int n) : n(n), t(4 * n), lz(4 * n) {}
void push(int p, int len) {
if (!lz[p])
return;
t[p] = len - t[p];
if (len > 1) {
lz[2 * p] ^= 1;
lz[2 * p + 1] ^= 1;
}
lz[p] = 0;
}
void update(int p, int l, int r, int x, int y) {
push(p, r - l);
if (r <= x || y <= l) {
return;
}
if (x <= l && r <= y) {
lz[p] = 1;
push(p, r - l);
return;
}
int m = (l + r) / 2;
update(2 * p, l, m, x, y);
update(2 * p + 1, m, r, x, y);
t[p] = t[2 * p] + t[2 * p + 1];
}
void update(int l, int r) {
update(1, 0, n, l, r);
}
int get(int p, int l, int r, int x) {
push(p, r - l);
if (l == r - 1) {
return t[p];
}
int m = (l + r) / 2;
if (x < m) {
return get(2 * p, l, m, x);
} else {
return get(2 * p + 1, m, r, x);
}
}
int get(int x) {
return get(1, 0, n, x);
}
};
constexpr int N = 1E5;
vector<int> e[N];
int deg[N];
int par[N], c[N], siz[N], h[N], in[N], out[N];
void dfs(int u, int p) {
h[u] = -1;
siz[u] = 1;
c[u] = e[u].size() == 1;
par[u] = p;
if (p != -1)
e[u].erase(find(e[u].begin(), e[u].end(), p));
for (int &v : e[u]) {
dfs(v, u);
c[u] ^= c[v];
siz[u] += siz[v];
if (siz[e[u][0]] < siz[v]) {
swap(e[u][0], v);
}
}
}
int timeStamp = 0;
int nxt[N];
void dfs2(int u) {
in[u] = timeStamp++;
for (int v : e[u]) {
nxt[v] = (v == e[u][0] ? nxt[u] : v);
dfs2(v);
}
out[u] = timeStamp;
}
SegmentTree s(N);
void update(int u) {
while (u != -1) {
s.update(in[nxt[u]], in[u] + 1);
u = par[nxt[u]];
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, nQ;
cin >> n >> nQ;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--;
v--;
e[u].push_back(v);
e[v].push_back(u);
deg[u]++;
deg[v]++;
}
int r = -1;
for (int i = 0; i < n; i++) {
if (deg[i] > 1) {
r = i;
}
}
dfs(r, -1);
nxt[r] = r;
dfs2(r);
for (int i = 0; i < n; i++)
if (c[i])
s.update(in[i], in[i] + 1);
while (nQ--) {
int k;
cin >> k;
vector<int> v(k);
for (int i = 0; i < k; i++) {
cin >> v[i];
v[i]--;
}
for (int x : v) {
deg[x]++;
if (deg[x] == 2)
continue;
update(x);
}
int cnt = n - s.t[1];
if (s.get(in[r]) == 0) {
cout << n + k + cnt - 2 << "\n";
} else {
cout << "-1\n";
}
for (int x : v) {
deg[x]--;
if (deg[x] == 1)
continue;
update(x);
}
}
return 0;
}
