#include <bits/stdc++.h>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
using namespace std;
const int MAX=1e5;
vector<vector<int>> neigh;
vector<int> val;
vector<int> sz;
vector<int> parent;
vector<pair<int,int>> block;
vector<int> indx;
vector<vector<int>> path;
vector<int> seg;
vector<int> lazy;
vector<int> ssz;
int root=0;
int lvs=0;
void dfs(int x, int p){
val[x]=0;
sz[x]=0;
parent[x]=p;
for (auto u : neigh[x])
{
if(u==p) continue;
dfs(u,x);
sz[x]+=sz[u];
val[x]+=val[u];
}
if(sz(neigh[x])==1) {
val[x]=1;
lvs++;
}
val[x]=val[x]%2;
}
void hld(int x, int p, int k){
int mx=-1;
path[k].push_back(x);
for (auto u : neigh[x]) {
if(u==p) continue;
mx=max(mx, sz[u]);
}
for (auto u : neigh[x])
{
if(u==p) continue;
if(sz[u]==mx) hld(u,x,k), mx=-1;
else path.push_back({}), hld(u,x,sz(path)-1);
}
}
void propagate(int x){
if(lazy[x]==1){
lazy[x]=0;
if(x*2+1<sz(seg)){
lazy[x*2]=(lazy[x*2]+1)%2;
seg[x*2]=ssz[x*2]-seg[x*2];
lazy[x*2+1]=(lazy[x*2+1]+1)%2;
seg[x*2+1]=ssz[x*2+1]-seg[x*2+1];
}
}
}
int query(int x, int l, int r, int ql, int qr){
if(r<ql||l>qr) return 0;
if(l>=ql&&r<=qr) return seg[x];
propagate(x);
int mid=(l+r)/2;
return query(x*2, l, mid, ql, qr)+query(x*2+1, mid+1, r, ql, qr);
}
void update(int x, int l, int r, int ql, int qr){
if(r<ql||l>qr) return;
if(l>=ql&&r<=qr) {
lazy[x]=(lazy[x]+1)%2;
seg[x]=ssz[x]-seg[x];
return;
}
propagate(x);
int mid=(l+r)/2;
update(x*2, l, mid, ql, qr);
update(x*2+1, mid+1, r, ql, qr);
seg[x]=seg[x*2]+seg[x*2+1];
}
void build(int x, int l, int r){
lazy[x]=0;
ssz[x]=r-l+1;
if(l==r) {
seg[x]=val[indx[l]];
return;
}
int mid=(l+r)/2;
build(x*2, l, mid);
build(x*2+1, mid+1, r);
seg[x]=seg[x*2]+seg[x*2+1];
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n,q; cin >> n >> q;
neigh.resize(n);
val.resize(n,-1);
sz.resize(n,-1);
seg.resize(4*n,-1);
lazy.resize(4*n,-1);
ssz.resize(4*n,-1);
block.resize(n);
parent.resize(n,-1);
for (int i = 0; i < n-1; i++)
{
int u,v; cin >> u >> v; u--; v--;
neigh[u].push_back(v);
neigh[v].push_back(u);
if(sz(neigh[u])>1) root=u;
if(sz(neigh[v])>1) root=v;
}
dfs(root,-1);
path.push_back({});
hld(root,-1,0);
int s=0;
for (int k = 0; k < sz(path); k++)
{
for (int i = 0; i < sz(path[k]); i++)
{
indx.push_back(path[k][i]);
block[path[k][i]]={s,s+i};
}
s+=sz(path[k]);
}
build(1,0,n-1);
vector<pair<int,int>> conn(n,{0,0});
for (int i = 0; i < q; i++)
{
int clvs=0;
int D; cin >> D;
vector<int> d(D);
for (int i = 0; i < D; i++) cin >> d[i];
vector<int> up;
//cerr << query(1,0,n-1,1,n-1) << " ";
for (int i = 0; i < D; i++)
{
conn[d[i]-1].first++;
if(conn[d[i]-1].first==1&&sz(neigh[d[i]-1])==1) continue;
int x=d[i]-1;
while(x!=-1){
//cerr << query(1,0,n-1,1,n-1) << " ";
up.push_back(x);
conn[x].second++;
x=parent[indx[block[x].first]];
}
clvs++;
}
for (auto u : up){
if(conn[u].second<0||conn[u].second%2==0) continue;
update(1,0,n-1,block[u].first,block[u].second);
conn[u].second=-1;
}
if((clvs+lvs)%2) cout << -1 << "\n";
else cout << 2*(n-1)-query(1,0,n-1,1,n-1)+D << "\n";
for (auto u : up){
if(conn[u].second==-1) update(1,0,n-1,block[u].first,block[u].second);
conn[u]={0,0};
}
for (int i = 0; i < D; i++) conn[d[i]-1]={0,0};
cerr << "\n";
}
return 0;
}
