#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pi;
typedef vector<int> vi;
typedef vector<vi> vvi;
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
struct Node{
int ones = 0,twos = 0;
int l, r;
bool isupd = 0;
Node *lc = nullptr, *rc = nullptr;
Node(int l, int r) : l(l), r(r) {
if(l != r){
lc = new Node(l,(l+r)/2);
rc = new Node((l+r)/2+1,r);
}
}
void update(){
if(isupd){
isupd = 0;
if(lc){
lc->isupd = !lc->isupd, rc->isupd = !rc->isupd;
swap(lc->ones,lc->twos);
swap(rc->ones,rc->twos);
}
}
if(lc){
ones = lc->ones + rc->ones;
twos = lc->twos + rc->twos;
}
}
void set_val(int i, int o, int t){
update();
if(i < l || i > r) return;
if(l == r) ones = o, twos = t;
else lc->set_val(i,o,t),rc->set_val(i,o,t);
update();
}
void flip_range(int i, int j){
update();
if(j < l || i > r) return;
if(i <= l && j >= r) swap(ones,twos), isupd = 1;
else lc->flip_range(i,j), rc->flip_range(i,j);
update();
}
int query(int i, int j){
update();
if(j < l || i > r) return 0;
if(i <= l && j >= r) return ones + 2*twos;
return lc->query(i,j) + rc->query(i,j);
}
};
pi operator+(pi a, pi b){
return {a.first + b.first, a.second + b.second};
}
struct Solver{
int N,R,ho = 1,LC=0;
vi S,F,H,HN,HT,EP,ISL;
vvi G,C;
Node *segt;
void DFS(int v, int prev = -1){
F[v] = prev;
if(G[v].size() == 1) EP[v] = ISL[v] = 1, LC++;
for(int u : G[v]){
if(u == prev) continue;
C[v].push_back(u);
DFS(u,v);
S[v] += S[u];
EP[v] += EP[u];
}
S[v]++;
if(!C[v].empty()) H[v] = *max_element(C[v].begin(),C[v].end(),[&](int a, int b){return S[a] < S[b];});
EP[v] %= 2;
}
void DFS2(int v, bool is_heavy = 0, int prev = -1){
HN[v] = ho++;
if(is_heavy) HT[v] = HT[F[v]];
else HT[v] = v;
if(H[v]) DFS2(H[v],1,v);
for(int u : C[v]){
if(u == H[v]) continue;
DFS2(u,0,v);
}
}
Solver(int N, int R, vvi G) : N(N), R(R), G(G) {
S.assign(N+1,0);
ISL = EP = F = H = HN = HT = S;
C.assign(N+1,{});
DFS(R);
DFS2(R);
segt = new Node(1,N);
for(int i = 1;i <= N;i++) segt->set_val(HN[i],EP[i],1-EP[i]);
}
void flip(int v){
for(;v != -1;v = F[HT[v]]){
segt->flip_range(HN[HT[v]],HN[v]);
}
}
int query(){
return segt->query(2,N);
}
};
int main(){
cin.sync_with_stdio(false);
cin.tie(NULL);
int N,Q,R,u,v,D;
cin >> N >> Q;
vvi G(N+1);
for(int i = 1;i < N;i++){
cin >> u >> v;
G[u].push_back(v);
G[v].push_back(u);
}
R = find_if(G.begin(),G.end(),[](vi &V){return V.size() > 1;}) - G.begin();
Solver S(N,R,G);
vi fl(N+1,-1);
vi L(1e5);
int ln;
for(;Q--;){
cin >> D;
ln = 0;
for(int i = 0;i < D;i++) cin >> L[i];
for(int i = 0;i < D;i++) if(S.ISL[L[i]] && fl[L[i]] == -1) fl[L[i]] = i, ln++;
if((S.LC + D - ln)%2){
cout << -1 << '\n';
}
else{
for(int i = 0;i < D;i++) if(fl[L[i]] != i) S.flip(L[i]);
cout << (S.query() + D) << '\n';
for(int i = 0;i < D;i++) if(fl[L[i]] != i) S.flip(L[i]);
}
for(int i = 0;i < D;i++) fl[L[i]] = -1;
}
}
