#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 int N = 2e5+5 , inf = 2e9 + 7;
const ll INF = 1e18 , mod = 1e9+7;
int P[N] , D[N] , H[N] , B[N] , pos[N] , NW;
int n , q , t[N*4] , a[N], b[N] , u[N*4] , sub[N] , cnt[N];
vector<int> g[N];
void upd(int v, int tl , int tr , int pos , int val){
if(tl == tr){
t[v] = val;
return;
}
int tm = (tl+tr) >> 1;
if(tm >= pos) upd(v*2,tl,tm,pos,val);
else upd(v*2+1,tm+1,tr,pos,val);
t[v] = t[v*2]+t[v*2+1];
}
void push(int v, int tl ,int tr){
if(tl == tr || u[v] == 0) return;
int tm = (tl+tr) >> 1;
t[v*2] = tm-tl+1-t[v*2];
t[v*2+1] = tr-tm-t[v*2+1];
u[v*2+1] ^= u[v];
u[v*2] ^= u[v];
u[v] = 0;
}
void updlr(int v, int tl , int tr , int l , int r){
push(v,tl,tr);
if(l <= tl && tr <= r){
t[v] = tr-tl+1-t[v];
u[v] = 1;
return;;
}
if(tl > r || tr < l) return;
int tm = (tl+tr) >> 1;
updlr(v*2,tl,tm,l,r);
updlr(v*2+1,tm+1,tr,l,r);
t[v] = t[v*2]+t[v*2+1];
}
int dfs(int v , int pr){
P[v] = pr;
D[v] = D[pr]+1;
int sz = 1;
int mx = 0;
sub[v] = 0;
for(int to : g[v]){
if(to != pr){
int tosz = dfs(to,v);
sz += tosz;
sub[v] += sub[to];
if(tosz > mx){
mx = tosz;
H[v] = to;
}
}
}
if(g[v].size() == 1) sub[v] = 1;
return sz;
}
void decompose(int v, int h){
B[v] = h;
pos[v] = ++NW;
// cout << sub[v] << " " << v << "\n";
upd(1,1,n,NW,1-sub[v]%2);
if(H[v]) decompose(H[v],h);
for(int to : g[v]){
if(to != P[v] && to != H[v]) decompose(to,to);
}
}
void update(int a , int b){
for(;; b = P[B[b]]){
// cout << B[b] <<" " << b << "\n";
updlr(1,1,n,pos[B[b]],pos[b]);
if(b == a) break;
if(B[b] == a) break;
}
}
void solve(){
cin >> n >> q;
NW = 0;
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 kol = 0;
int st = 1;
for(int i = 1; i <= n; i++){
if(g[i].size() != 1){
st = i;
break;
}
}
for(int i = 1; i <= n; i++){
if(g[i].size() == 1) kol++;
}
dfs(st,st);
decompose(st,st);
while(q--){
int k;
cin >> k;
set<int> stt;
for(int i = 1; i <= k; i++){
int a;
cin >> a;
cnt[a]++;
stt.insert(a);
}
for(auto x : stt){
int nw = (cnt[x]-(g[x].size() == 1));
kol += nw;
if(nw%2) update(st,x);
}
if(kol % 2 == 1) cout << "-1\n";
else cout << t[1]+n+k-2 << "\n";
for(auto x : stt){
int nw = (cnt[x]-(g[x].size() == 1));
kol -= nw;
if(nw%2) update(st,x);
cnt[x] = 0;
}
}
}
/*
*/
signed main(){
ios;
solve();
return 0;
}
