#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
using namespace std;
/*
LCA solution, it works when you don't know the ith question before answering the i-1th
Note that this is an O(NlogN) solution
Made for you by Mate Busa
*/
int N, Q, a, b, cur, num, o, ans, root, dif, last, level, oo;
vector<int> neighbour[200000];
bool visited[200000];
int dis[200000];
int parent[200000];
int order[200000][2];
int number[200000];
int dp[200000];
int fia[200000];
int f[200000];
vector<int> d[200000];
set<int> reuse;
set<int> who;
vector<int> vec;
void dfs(int x){
visited[x] = true; order[x][0] = cur++; oo++;
if(root==x){
parent[x] = -1;
} else {
int hat = 0; while((1<<hat)<=dis[x]) hat++;
d[x].resize(hat); d[x][0] = parent[x];
for(int i=1; i<hat; i++) d[x][i] = d[d[x][i-1]][i-1];
}
bool lv = true;
for(int i:neighbour[x]){
if(!visited[i]){
dis[i] = dis[x]+1; parent[i] = x;
dfs(i); lv = false; dp[x] += dp[i];
}
}
if(lv) dp[x]++;
if(dp[x]%2==0) o++;
order[x][1] = cur++;
}
void pre(int x){
for(int i:neighbour[x]){
if(parent[x]!=i){
dp[i] = dp[i]%2 + dp[x];
pre(i);
}
}
}
int lca(int x, int y){
if(dis[y]<dis[x]) swap(x,y);
for(int i=d[y].size()-1; dis[x]!=dis[y]; i--){
if(dis[y]-(1<<i)>=dis[x]) y = d[y][i];
}
if(x==y) return x;
for(int i=d[x].size()-1; parent[x]!=parent[y]; i--){
if((1<<i)<=dis[x] && d[x][i]!=d[y][i]){x = d[x][i]; y = d[y][i];}
}
return parent[x];
}
bool smaller(int x, int y){
return order[x][dif] < order[y][dif];
}
int calc(int x){
return (dp[x]-(dis[x]+1-dp[x]));
}
///find parent in LCA tree
void up(){
if(number[a]%2==1){
ans += calc(a);
if(f[a]!=-1) ans -= calc(f[a]);
}
if(f[a]!=-1) number[f[a]] += number[a];
a = f[a];
}
int main()
{
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr); std::cout.tie(nullptr);
cin >> N >> Q;
for(int i=0; i<N-1; i++){
cin >> a >> b;
neighbour[a-1].push_back(b-1);
neighbour[b-1].push_back(a-1);
}
///find an inside point
for(int i=0; i<N; i++) if(neighbour[i].size()!=1) {root = i; break;}
dfs(root); level = dp[root];
dp[root] %= 2; pre(root);
for(int ii=0; ii<Q; ii++){
reuse.clear(); vec.clear(); who.clear(); ans = N-1+o;
cin >> num; ans += num;
for(int i=0; i<num; i++){
cin >> a; number[a-1]++; reuse.insert(a-1);
}
for(int i:reuse){
if((neighbour[i].size()==1 && number[i]>=2 && number[i]%2==0) || (neighbour[i].size()>1 && number[i]%2==1)){
vec.push_back(i); number[i] = 1;
} else {
number[i] = 0;
}
}
if((level+vec.size())%2==1){
cout << -1 << '\n';
for(int i:vec) number[i] = 0;
} else {
if(vec.size()!=0){
dif = 1; sort(vec.begin(),vec.end(),smaller);
last = -1;
for(int i:vec){
who.insert(i);
if(last!=-1) who.insert(lca(last,i));
last = i;
}
cur = 0;
for(int i:who) fia[cur++] = i;
dif = 0; sort(fia,fia+cur,smaller);
f[fia[0]] = -1; a = fia[0];
for(int i=1; i<cur; i++){
while(order[a][1]<order[fia[i]][0]) up();
f[fia[i]] = a; a = fia[i];
}
while(a!=-1) up();
for(int i=0; i<cur; i++) number[fia[i]] = 0;
}
cout << ans-1 << '\n';
}
}
return 0;
}
