#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<int, int> pii;
#define SZ(x) (int) x.size()
#define F first
#define S second
#define lc id << 1
#define rc lc | 1
const int N = 1e5 + 10;
int leaf[N], A[N], seg[N << 2], lz[N << 2], St[N], M[N], H[N], S[N], HD[N], P[N], C[N], n, q, tim, rt;
vector<int> adj[N];
void shift(int id, int l, int r) {
if (!lz[id]) return;
seg[id] = r - l - seg[id];
if (r - l > 1) {
lz[lc] ^= 1, lz[rc] ^= 1;
}
lz[id] = 0;
}
void update(int ql, int qr, int x, int id = 1, int l = 0, int r = tim) {
shift(id, l, r);
if (qr <= l || r <= ql) return;
if (ql <= l && r <= qr) {
lz[id] ^= x;
return shift(id, l, r);
}
int mid = (l + r) >> 1;
update(ql, qr, x, lc, l, mid);
update(ql, qr, x, rc, mid, r);
seg[id] = seg[lc] + seg[rc];
}
void preDFS(int v, int p = -1) {
P[v] = p, C[v] = (SZ(adj[v]) == 1), S[v] = 1;
for (int u : adj[v]) {
if (u != p) H[u] = H[v] + 1, preDFS(u, v), S[v] += S[u], C[v] += C[u];
}
for (int u : adj[v]) if (S[M[v]] < S[u] && u != p) M[v] = u;
}
void HLD(int v, int p = -1) {
if (p == -1) HD[v] = v;
St[v] = tim++;
if (M[v]) HD[M[v]] = HD[v], HLD(M[v], v);
for (int u : adj[v]) {
if (u != M[v] && u != p) HD[u] = u, HLD(u, v);
}
}
int get(int id = 1, int l = 0, int r = tim) {
shift(id, l, r);
if (r - l == 1) return seg[id];
int mid = (l + r) >> 1;
return get(lc, l, mid);
}
int main() {
scanf("%d%d", &n, &q);
for (int i = 1; i < n; i++) {
int u, v; scanf("%d%d", &u, &v);
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; i++) if (SZ(adj[i]) > 1) rt = i;
preDFS(rt);
HLD(rt);
for (int i = 1; i <= n; i++) {
update(St[i], St[i] + 1, !(C[i] & 1));
}
for (; q; q--) {
int k; scanf("%d", &k);
for (int i = 1; i <= k; i++) {
scanf("%d", &A[i]);
int v = A[i];
if (SZ(adj[v]) == 1 && !leaf[v]) {
leaf[v] = 1;
int u = v;
while (~u) {
update(St[HD[u]], St[u] + 1, 1);
u = P[HD[u]];
}
}
while (~v) {
update(St[HD[v]], St[v] + 1, 1);
v = P[HD[v]];
}
}
int t = get();
if (!(t & 1)) printf("-1\n");
else printf("%d\n", n + k + seg[1] - 2);
for (int i = 1; i <= k; i++) {
if (leaf[A[i]]) {
int u = A[i];
while (~u) {
update(St[HD[u]], St[u] + 1, 1);
u = P[HD[u]];
}
leaf[A[i]] = 0;
}
int v = A[i];
while (~v) {
update(St[HD[v]], St[v] + 1, 1);
v = P[HD[v]];
}
}
}
return 0;
}
