#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define s second
#define f first
#define left (h<<1),l,((l + r)>>1)
#define right ((h<<1)|1),((l + r)>>1) + 1,r
#define pii pair <int,int>
using namespace std;
const int N = 2e5 + 5;
vector <int> v[N];
int head[N],heavy[N],timer,tin[N],lz[4*N];
int parent[N],t[4*N],n,fix[N],sub[N],root;
vector <pii> vec;
void push(int h,int l,int r){
if (!lz[h]) return;
lz[h*2] ^= 1;
lz[h*2+1]^=1;
int mid=(l+r)/2;
t[h*2]=(mid - l + 1) - t[h*2];
t[h*2+1] = (r - mid) - t[h*2 + 1];
lz[h]=0;
}
void upd(int h,int l,int r,int L,int R){
if (r < L || R < l) return;
if (L <= l && r <= R){
lz[h] ^= 1;
t[h] = (r - l + 1) - t[h];
return;
}
push(h,l,r);
upd(left,L,R);
upd(right,L,R);
t[h] = t[h*2] + t[h*2 + 1];
}
void dfs(int x){
sub[x] = 1;
for (int to: v[x]){
if (to == parent[x]) continue;
parent[to] = x;
dfs(to);
sub[x] += sub[to];
if (sub[to] > sub[heavy[x]]) heavy[x] = to;
}
}
void dfs2(int x,int hh){
head[x] = hh;
tin[x] = ++timer;
if (heavy[x]) dfs2(heavy[x],hh);
for (int to: v[x]){
if (to==parent[x] || to == heavy[x]) continue;
dfs2(to,to);
}
}
void update(int x){
while (x != root){
upd(1,1,n,tin[head[x]],tin[x]);
if (head[x] == root) return;
x = parent[head[x]];
}
upd(1,1,n,1,1);
}
int main() {
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int m;
cin>>n>>m;
for (int i = 1; i < n; i++){
int a,b;
cin>>a>>b;
v[a].pb(b);
v[b].pb(a);
}
// for (int i= 1; i <= n; i++){
// if (v[i].size() > 1) {root = i; break;}
// }
root = 1;
dfs(root);
dfs2(root,root);
int LL=0;
for (int i = 1; i <= n; i++){
if (v[i].size() == 1) update(i),LL++;
}
for (int j = 1; j <= m; j++){
int x;
cin>>x;
int L=LL;
vector <int> vert;
for (int i = 1; i <= x; i++){
int nd;
cin>>nd;
if (!fix[nd] && v[nd].size() == 1){
--L;
fix[nd] = 1;
}
else {
update(nd);
}
vert.pb(nd);
}
L += x;
if (!(L%2))
cout<<2*n + x - 2 - t[1]<<endl;
else
cout<<-1<<endl;
for (int y: vert) fix[y]=0;
for (int nd: vert){
if (!fix[nd] && v[nd].size() == 1){
--L;
fix[nd] = 1;
}
else {
update(nd);
}
}
for (int y: vert) fix[y]=0;
}
}
