#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;
int a[N], b[N], siz[N], par[N], d[N], t[N*4], tin[N], path[N];
int n,m,sum=0,x,y, ans, r, cnt[N], l, mod = 1e9+7, inf = -1e18, k, root, timer = 1, heavy[N];
string s, str;
vector<int>g[N];
void push(int v, int l, int r){
if(!d[v])return;
if(l != r)d[v*2] ^= 1, d[v*2+1] ^= 1;
t[v] = r-l+1-t[v];
d[v] = 0;
}
void UPD(int l, int r, int v = 1, int tl = 1, int tr = n){
push(v, tl, tr);
if(l <= tl && tr <= r){
t[v] = tr-tl+1-t[v];
d[v*2] ^= 1, d[v*2+1] ^= 1;
return;
}
if(l > tr || tl > r)return;
int tm = (tl + tr) >> 1;
UPD(l, r, v*2, tl, tm), UPD(l, r, v*2+1, tm+1, tr);
t[v] = t[v*2+1] + t[v*2];
}
void update(int pos){
while(1){
UPD(tin[pos], tin[path[pos]]);
pos = path[pos];
pos = par[pos];
if(pos == root || pos == 0)return;
}
}
void upd(int v, int tl, int tr, int pos){
if(tl == tr){
t[v] ++;
return;
}
int tm = (tl + tr) >> 1;
if( pos <= tm )upd(v*2, tl, tm, pos);
else upd(v*2+1, tm+1, tr, pos);
t[v] = t[v*2] + t[v*2+1];
}
void dfs(int v, int p = 0){
par[v] = p;
int H = 0;
for(auto i : g[v]){
if(i != p){
dfs(i, v);
siz[v] += siz[i];
if(siz[i] > H)heavy[v] = i, H = siz[i];
}
}
if(g[v].sz==1)siz[v] = 1;
}
void HLD(int v, int h){
path[v] = h;
tin[v] = timer++;
if(siz[v] % 2 == 0 && v != root)upd(1, 1, n, tin[v]);
if( heavy[v] )HLD(heavy[v], h);
for(auto i : g[v]){
if(i != par[v] && i != heavy[v])HLD(i, i);
}
}
void solve(){
cin >> n >> m;
FOR(i, 2, n, 1){
cin >> x >> y;
g[x].pb(y), g[y].pb(x);
}
FOR(i, 1, n, 1){
if(g[i].sz!=1){
root = i;
break;
}
}
int list = 0;
FOR(i, 1, n, 1)list += (g[i].sz == 1);
dfs(root);
tin[root] = timer++;
for(auto i : g[root])HLD(i, i);
FOR(i, 1, m, 1){
cin >> k;
set<int>st;
FOR(j, 1, k, 1){
cin >> x;
cnt[x]++;
st.in(x);
}
for(auto j : st){
list += cnt[j] - (g[j].sz == 1);
if((cnt[j]-(g[j].sz==1))%2)update(j);
}
if(list%2){
cout << "-1\n";
}
else cout << t[1] + n + k - 1 << '\n';
for(auto j : st){
list -= cnt[j] - (g[j].sz == 1);
if((cnt[j]-(g[j].sz==1))%2)update(j);
cnt[j] = 0;
}
}
}
signed main(){
nikita
int tt = 1;
if(!tt)cin >> tt;
FOR(i, 1, tt, 1){
solve();
}
}
