#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
typedef pair<int,int> pi;
typedef vector <int> vi;
typedef vector <pi> vpi;
typedef pair<pi, ll> pii;
typedef set <ll> si;
typedef long double ld;
#define f first
#define s second
#define mp make_pair
#define FOR(i,s,e) for(int i=s;i<=int(e);++i)
#define DEC(i,s,e) for(int i=s;i>=int(e);--i)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
#define aFOR(i,x) for (auto i: x)
#define mem(x,i) memset(x,i,sizeof x)
#define fast ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
#define maxn 300010
#define INF (ll)(1e18+10)
#define MOD 998244353
typedef pair <vi, int> pvi;
typedef pair <int,pi> ipi;
typedef vector <pii> vpii;
typedef pair <pi,pi> pipi;
int TC;
vi adj[maxn];
int sz[maxn], heavy[maxn], depth[maxn], head[maxn], st[maxn], par[maxn];
void dfs(int x,int p){
sz[x] = 1;
par[x] = p;
heavy[x] = -1;
aFOR(i,adj[x]) if (i != p){
depth[i] = depth[x] + 1;
dfs(i,x);
sz[x] += sz[i];
if (heavy[x] == -1 || sz[heavy[x]] < sz[i]) heavy[x] = i;
}
}
int co = 1;
void hld(int x, int h){
head[x] = h; st[x] = co++;
if (heavy[x] != -1) hld(heavy[x], h);
aFOR(i, adj[x]) if (i != heavy[x] && i != par[x]){
hld(i, i);
}
}
struct node{
int s,e,m,val=0; // val is the number of odds
bool lazy = 0;
node *l, *r;
node(int ss,int ee){
s = ss; e = ee; m = (s + e) / 2;
if (s != e){
l = new node(s,m); r = new node(m+1,e);
}
}
void prop(){
if (s == e || !lazy) return;
l->lazy = !l->lazy; r->lazy = !r->lazy;
l->val = (l->e - l->s + 1) - l->val;
r->val = (r->e - r->s + 1) - r->val;
lazy = 0;
}
void flip(int a,int b){
prop();
if (a <= s && e <= b){
val = (e - s + 1) - val;
lazy = !lazy;
}else if (a > e || s > b) return;
else{
l->flip(a, b); r->flip(a,b);
val = l->val + r->val;
}
}
}*root;
void upd(int x){ // flip from x to root
while (x != -1){
root->flip(st[head[x]], st[x]);
x = par[head[x]];
}
}
int a,b;
int N,Q,d;
int deg[maxn];
int32_t main(){
fast;
cin >> N >> Q;
FOR(i,1,N-1){
cin >> a >> b; adj[a].pb(b); adj[b].pb(a);
}
dfs(1,-1);
hld(1,1);
root = new node(1,N);
int num = 0;
FOR(i,1,N) deg[i] = adj[i].size();
FOR(i,1,N) if (adj[i].size() == 1){
num++; upd(i);
}
FOR(i,1,Q){
cin >> d;
int nnum = num;
vi v;
FOR(j,1,d){
cin >> a;
if (deg[a] == 1){
upd(a); nnum--;
}
deg[a]++;
v.pb(a);
}
if ((nnum+d) % 2 == 1){
cout << -1 << '\n';
}else{
aFOR(i, v) upd(i);
cout << (N - 1 - root->val) + (N-1) + d << '\n';
aFOR(i, v) upd(i);
}
aFOR(i,v){
deg[i]--;
if (deg[i] == 1) upd(i);
}
}
}
