#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define in insert
#define lb lower_bound
#define F first
#define S second
#define sz size()
#define int long long
#define all(v) v.begin(),v.end()
#define FOR1(x, n) for(int j = x; j <= n; j ++)
#define FOR(x, n, m, d) for(int x = n; x <= m; x += d)
#define FORR(x, n, m, d) for(int x = n; x >= m; x -= d)
#define nikita ios_base::sync_with_stdio(0), cin.tie(0);
const int N = 1e6+5, M = 210;
int a[N], b[N], pref[N], d[N], c[N], tin[N], timer = 0, tout[N], t[N];
int n,m,k,sum=0,x,y, ans, r, cnt, l,inf = -1e18, dist[N], par[N];
string s, str;
vector<int>g[N];
bool f = 0;
void dfs(int v, int p = 0){
tin[v] = ++timer;
for(auto i : g[v]){
if(i != p)dfs(i, v);
}
sum = 0;
for(auto i : g[v]){
if(i != p)sum += d[i];
}
ans += sum;
if(sum % 2 || g[v].sz == 1)d[v] = 1;
else d[v] = 2;
tout[v] = timer;
}
void sol(int v, int p = 0){
par[v] = p;
if(v!=1){
dist[v] = dist[p]+1;
c[v] = c[p] + (d[v] == 2);
}
for(auto i : g[v]){
if(i != p)sol(i, v);
}
}
void jump(int v){
if(v==1)return;
sum += 1 * (d[v] == 2 ? 1 : -1);
if(d[v]==2)d[v] = 1;
else d[v] = 2;
jump(par[v]);
}
void solve(){
cin >> n >> m;
FOR(i, 2, n, 1){
cin >> x >> y;
g[x].pb(y), g[y].pb(x);
}
int lp = 0;
FOR(i, 1, n, 1){
lp += (g[i].sz==1);
}
sum = ans = 0;
dfs(1);
sol(1);
int op = ans;
FOR(i, 1, m, 1){
cin >> k;
int ko = 0;
ans = 0;
FOR(j, 1, k, 1){
cin >>a[i];
x = a[i];
if(!pref[x] && g[x].sz==1)pref[x] = 1, ko ++;
sum = 0;
jump(x);
ans += sum;
}
FOR(j, 1, k, 1)pref[a[i]]=0;
if((lp + k - ko) % 2){cout << "-1\n";continue;}
cout << ans + k + op << '\n';
}
}
signed main() {
nikita
int tt = 1;
if(!tt)cin >> tt;
FOR(i, 1, tt, 1) {
solve();
}
}
