#include <bits/stdc++.h>
#define ios ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define file(s) if (fopen(s".in", "r")) freopen(s".in", "r", stdin), freopen(s".out", "w", stdout)
#define all(a) a.begin() , a.end()
#define F first
#define S second
using namespace std;
using ll = long long;
const ll N = 2e5+5 , inf = 2e9 + 7;
const ll INF = 1e18 , mod = 1e9+7;
ll a[N] , b[N] , sz[N] , par[N] , cnt[N];
vector<int> g[N];
int ans = 0;
void go(int v , int p){
par[v] = p;
sz[v] = 0;
for(int to : g[v]){
if(to != p){
go(to,v);
sz[v] += sz[to];
}
}
if(g[v].size() == 1) sz[v] = 1;
if(sz[v] % 2 == 0) ans++;
}
void add(int x , int kol , int p){
while(x > 0){
if(sz[x] % 2 == 0) ans--;
sz[x] += kol;
if(sz[x] % 2 == 0) ans++;
x = par[x];
}
}
void solve(){
int n , q;
cin >> n >> q;
for(int i = 1; i < n; i++){
cin >> a[i] >> b[i];
g[a[i]].push_back(b[i]);
g[b[i]].push_back(a[i]);
}
int bas = 1;
for(int i = 1; i <= n; i++){
if(g[i].size() != 1){
bas = i;
break;
}
}
go(bas,0);
while(q--){
int k;
cin >> k;
set<int> st;
for(int i = 1; i <= k; i++){
int a;
cin >> a;
cnt[a]++;
st.insert(a);
}
for(auto x : st){
add(x,cnt[x]-(g[x].size() == 1),0);
}
if(sz[bas] % 2 == 1) cout << "-1\n";
else cout << ans+n+k-2 << "\n";
for(auto x : st){
add(x,-(cnt[x]-(g[x].size() == 1)),0);
cnt[x] = 0;
}
}
}
/*
*/
signed main(){
ios;
solve();
}
