#include <bits/stdc++.h>
#define all(x) x.begin(), x.end()
#define pb push_back
#define fi first
#define se second
using namespace std;
typedef long long ll;
const int MAXN = 200005;
int n, q, ans, sz;
int u[MAXN], v[MAXN], dp[MAXN], par[MAXN], dp2[MAXN];
vector < int > g[MAXN], vec;
void dfs(int v, int p){
dp[v] = (g[v].size() == 1);
for(int u : g[v]){
if(u == p) continue;
dfs(u, v), par[u] = v, dp[v] += dp[u];
}
if(v == 1) dp[v] = 0;
while(dp[v] > 2) dp[v] -= 2;
ans += dp[v];
dp2[v] = dp[v];
}
void up(ll v){
if(v == 1) return;
ans -= dp[v];
dp[v]++;
if(dp[v] > 2) dp[v] -= 2;
vec.pb(v);
ans += dp[v];
up(par[v]);
}
signed main(){
int d, x, cnt, pcnt = 0, cur;
vector < int > del;
cin >> n >> q, sz = n;
for(int i = 1; i < n; i++) cin >> u[i] >> v[i], g[u[i]].pb(v[i]), g[v[i]].pb(u[i]);
for(int i = 1; i <= n; i++) pcnt += (g[i].size() == 1);
dfs(1, 1), cur = ans;
while(q--){
vec.clear();
cnt = pcnt, ans = cur, sz = n, del.clear(), cin >> d;
while(d--){
cin >> x, del.pb(x);
sz++, cnt = cnt + 1 - (g[x].size() == 1);
g[x].pb(sz), g[sz].pb(x);
par[sz] = x, up(sz);
}
for(auto it : vec) dp[it] = dp2[it];
if(cnt % 2){
while(!del.empty()) g[del.back()].pop_back(), del.pop_back();
for(ll i = n + 1; i <= sz; i++) g[i].clear();
cout << "-1\n"; continue;
}
while(!del.empty()) g[del.back()].pop_back(), del.pop_back();
for(ll i = n + 1; i <= sz; i++) g[i].clear();
cout << ans << '\n';
}
}
/*
g++ cleaning.cpp -o program.exe
program.exe
7 3
1 2
2 4
4 5
5 6
5 7
3 4
1 4
2 2 4
1 1
*/
