#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = (a), _b = (b); i <= _b; ++i)
#define REP(i, a, b) for(int i = (a), _b = (b); i >= _b; --i)
#define mp make_pair
#define all(v) v.begin(), v.end()
#define uni(v) v.erase(unique(all(v)), v.end())
#define Mask(i) (1 << (i))
#define Bit(x, i) (((x) >> (i)) & 1)
const int mod = 1e9 + 7;
int fastPow(int a, int n){
if(n == 0) return 1;
int t = fastPow(a, n >> 1);
t = 1ll * t * t % mod;
if(n & 1) t = 1ll * t * a % mod;
return t;
}
bool minimize(int &u, int v) { return u > v ? u = v, true : false;}
bool maximize(int &u, int v) { return u < v ? u = v, true : false;}
bool minimizell(long long &u, long long v) { return u > v ? u = v, true : false;}
bool maximizell(long long &u, long long v) { return u < v ? u = v, true : false;}
const int maxN = 1e5 + 5;
int n, q;
vector<int> adj[maxN];
vector<int> query[maxN];
int numNode[maxN];
namespace subtask2{
bool check(){
return n <= 20000 && q <= 300;
}
const int maxN = 20005;
int orgN;
long long answer = 0;
int numLeaves[maxN];
void dfs(int u, int p){
numLeaves[u] = 0;
if(u != 1){
if(adj[u].size() == 1){
numLeaves[u] = 1;
return;
}
}
for(int v : adj[u]){
if(v == p) continue;
dfs(v, u);
answer += numLeaves[v];
numLeaves[u] += numLeaves[v];
}
if(numLeaves[u] % 2 == 1)numLeaves[u] = 1;
else numLeaves[u] = 2;
}
void solve(){
orgN = n;
FOR(i, 1, q) {
n = orgN;
// for(int u : query[i])cout << u << ' ';cout << '\n';
for(int u : query[i]){
adj[u].emplace_back(++n);
adj[n].emplace_back(u);
}
int numLeaves = 0;
FOR(i, 1, n){
if(adj[i].size() == 1)++numLeaves;
}
if(numLeaves % 2 == 1){
FOR(i, 1, orgN){
while(!adj[i].empty() && adj[i].back() > orgN) adj[i].pop_back();
}
FOR(i, orgN + 1, n)adj[i].clear();
cout << -1 << '\n';
continue;
}
answer = 0;
dfs(1, 0);
cout << answer << '\n';
FOR(i, 1, orgN){
while(!adj[i].empty() && adj[i].back() > orgN) adj[i].pop_back();
}
FOR(i, orgN + 1, n)adj[i].clear();
}
}
}
namespace ac{
int numLeaves[maxN];
long long rem = 0;
int chain[maxN], curChain = 1, top[maxN], arr[maxN], lab[maxN], curLab = 1, sz[maxN], par[maxN];
void dfs(int u = 1, int p = 0){
if(u != 1){
if(adj[u].size() == 1){
numLeaves[u] = 1;
return;
}
}
sz[u] = 1;
for(int v : adj[u]){
if(v == p) continue;
par[v] = u;
dfs(v, u);
sz[u] += sz[v];
numLeaves[u] += numLeaves[v];
rem += numLeaves[v];
}
if(numLeaves[u] % 2 == 0)numLeaves[u] = 2;
else numLeaves[u] = 1;
}
void hld(int u = 1, int p = 0){
if(top[curChain] == 0) top[curChain] = u;
chain[u] = curChain;
lab[u] = curLab;
arr[curLab] = u;
++curLab;
int h = 0;
for(int v : adj[u]){
if(v == p) continue;
if(sz[v] > sz[h]) h = v;
}
if(h) hld(h, u);
for(int v : adj[u]){
if(v != h && v != p){
++curChain;
hld(v, u);
}
}
}
struct Node{
int cnt1, cnt2;
Node(int _cnt1 = 0, int _cnt2 = 0){
cnt1 = _cnt1;
cnt2 = _cnt2;
}
Node operator + (const Node &rhs) const{
Node res;
res.cnt1 = cnt1 + rhs.cnt1;
res.cnt2 = cnt2 + rhs.cnt2;
return res;
}
}it[maxN << 2];
int lz[maxN << 2];
void push(int id){
if(lz[id] == 0) return;
lz[id << 1] ^= 1;
lz[id << 1 | 1] ^= 1;
swap(it[id << 1].cnt1, it[id << 1].cnt2);
swap(it[id << 1 | 1].cnt1, it[id << 1 | 1].cnt2);
lz[id] = 0;
return;
}
void build(int id, int l, int r){
if(l == r){
int u = arr[l];
if(numLeaves[u] == 2) it[id].cnt2 = 1;
else it[id].cnt1 = 1;
return;
}
int mid = l + r >> 1;
build(id << 1, l, mid);
build(id << 1 | 1, mid + 1, r);
it[id] = it[id << 1] + it[id << 1 | 1];
}
void update(int id, int l, int r, int u, int v){
if(l > v || r < u) return;
if(l >= u && r <= v){
swap(it[id].cnt1, it[id].cnt2);
lz[id] ^= 1;
return;
}
push(id);
int mid = l + r >> 1;
update(id << 1, l, mid, u, v);
update(id << 1 | 1, mid + 1, r, u, v);
it[id] = it[id << 1] + it[id << 1 | 1];
}
Node get(int id, int l, int r, int u, int v){
if(l >= u && r <= v) return it[id];
int mid = l + r >> 1;
push(id);
if(v <= mid) return get(id << 1, l, mid, u, v);
if(u > mid) return get(id << 1 | 1, mid + 1, r, u, v);
Node L = get(id << 1, l, mid, u, v);
Node R = get(id << 1 | 1, mid + 1, r, u, v);
return L + R;
}
long long getNode(int u){
Node answer;
while(chain[u] != chain[1]){
answer = answer + get(1, 1, n, lab[top[chain[u]]], lab[u]);
u = par[top[chain[u]]];
}
if(u != 1) answer = answer + get(1, 1, n, lab[1] + 1, lab[u]);
return answer.cnt1 + 2 * answer.cnt2;
}
void change(int u){
while(chain[u] != chain[1]){
update(1, 1, n, lab[top[chain[u]]], lab[u]);
u = par[top[chain[u]]];
}
if(u != 1) update(1, 1, n, lab[1] + 1, lab[u]);
}
int deg[maxN];
int cnt[maxN];
bool Leaves[maxN];
void solve(){
dfs();
hld();
build(1, 1, n);
FOR(i, 1, n)deg[i] = adj[i].size();
int orgLeaves = 0;
FOR(i, 1, n)if(deg[i] <= 1)++orgLeaves;
FOR(i, 1, n)Leaves[i] = deg[i] <= 1;
// cout << orgLeaves << '\n';
FOR(i, 1, q){
int curLeaves = orgLeaves;
for(int u : query[i]){
if(deg[u] <= 1)--curLeaves;
++curLeaves;
deg[u]++;
cnt[u]++;
}
sort(all(query[i]));
uni(query[i]);
if(curLeaves % 2 == 1){
cout << -1 << '\n';
for(int u : query[i]){
deg[u] = adj[u].size();
cnt[u] = 0;
}
continue;
}
long long answer = rem;
for(int u : query[i]){
if(Leaves[u]){
answer += cnt[u];
if(cnt[u] % 2 == 0){
answer -= getNode(u);
change(u);
answer += getNode(u);
}
}else{
answer += cnt[u];
if(cnt[u] % 2 == 1) {
answer -= getNode(u);
change(u);
answer += getNode(u);
}
}
}
cout << answer << '\n';
for(int u : query[i]){
if(Leaves[u]){
// answer += cnt[u];
if(cnt[u] % 2 == 0)change(u);
}else{
// answer += cnt[u];
if(cnt[u] % 2 == 1) change(u);
}
}
for(int u : query[i]){
deg[u] = adj[u].size();
cnt[u] = 0;
}
}
}
}
void process(){
cin >> n >> q;
FOR(i, 1, n - 1){
int u, v;
cin >> u >> v;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
FOR(i, 1, q){
cin >> numNode[i];
query[i].resize(numNode[i]);
for(int &u : query[i])cin >> u;
}
if(subtask2 :: check()) return subtask2 :: solve();
return ac :: solve();
}
//#define LOVE "crt"
int main(){
// freopen(LOVE".inp", "r", stdin);
// freopen(LOVE".out", "w", stdout);
ios_base :: sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
process();
return 0;
}
/*
7 3
1 2
2 4
4 5
5 6
5 7
3 4
1 4
2 2 4
1 1
7 3
1 2
2 4
4 5
5 7
3 4
4 1 1 2 6
3 6 6 6 2
2 2 7
*/
