#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define tiii tuple<int,int,int>
using namespace std;
int n;
vector<vector<int>> adj;
void DFS(int v, int p, vector<int>& dp, vector<vector<int>>& adj, vector<int>& arr){
dp[v] = arr[v];
if(adj[v].size() == 1 && arr[v] == 0){
dp[v]++;
}
for(auto u : adj[v]){
if(u == p) continue;
DFS(u,v,dp,adj,arr);
dp[v] += dp[u];
}
}
int solve(vector<vector<int>>& adj, int d){
vector<int> arr(n);
for(int i = 0; i < d; i++){
int a;
cin >> a;
a--;
arr[a]++;
}
int r = 0;
for(int i = 0; i < n; i++){
if(adj[i].size() > 1){
r = i;
break;
}
}
vector<int> dp(n);
DFS(r,r,dp,adj, arr);
if(dp[r] % 2 == 1){
return -1;
}
int cnt = 0;
for(int i = 0; i < n; i++){
if(dp[i] % 2 == 0){
cnt++;
}
}
return n + d + cnt - 2;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int q;
cin >> n>> q;
vector<vector<int>> adj(n);
for(int i = 0; i < n-1; i++){
int a,b;
cin >> a >> b;
a--;b--;
adj[a].push_back(b);
adj[b].push_back(a);
}
while(q--){
int d;
cin >> d;
cout << solve(adj, d) << "\n";
}
}
