#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <math.h>
#include <set>
#include <map>
#include <fstream>
#include <unordered_map>
#include <queue>
#define NEK 1000000000
#define ll long long
#define vec vector
#define For(i, n) for(int i = 0; i < n; i++)
#define ld long double
#define pii pair<int, int>
#define ff first
#define int ll
#define ss second
#define ld long double
#define mod 1000000007
#define sig 0.000001
#define all(x) x.begin(), x.end()
using namespace std;
class intervalac{
vec<int> in, lp, l, r;
int n;
void apply(int s){
in[s] = 3 * (r[s] - l[s] + 1) - in[s];
lp[s] = 1 - lp[s];
return;
}
void propagate(int s){
if(lp[s] == 0) return;
apply(s*2);
apply(s*2 + 1);
lp[s] = 0;
return;
}
void update(int s){
in[s] = in[s*2] + in[s*2 + 1];
return;
}
public:
intervalac(int vel){
n = 1;
while(n < vel) n*= 2;
in.resize(2*n, 0);
l.resize(2*n); r.resize(2*n);
lp.resize(2*n, 0);
For(i, n){
l[i+n] = r[i+n] = i;
}
for(int i = n-1; i >= 1; i--){
l[i] = l[i*2];
r[i] = r[i*2 + 1];
}
}
void zmen(int a, int b){
a+=n;
in[a] = b;
a/=2;
while(a){
update(a);
a/=2;
}
return;
}
int daj(int a, int b, int s = 1){
if(l[s] > b || r[s] < a) return 0;
if(a <= l[s] && r[s] <= b) {
int vel = r[s] - l[s] + 1;
int pv = in[s];
apply(s);
return 3 * vel - 2 * pv;
}
propagate(s);
update(s);
return daj(a, b, s*2) + daj(a, b, s*2 + 1);
}
};
vec<vec<int>> g;
vec<int> vrst;
vec<int> par;
vec<int> o;
vec<int> nxt;
vec<int> pd;
vec<int> e;
int ti = 0;
int dfs(int x, int pr = -1){
o[x] = pr;
pd[x] = 1;
par[x] = 0;
for(auto i : g[x]){
if(i == pr) continue;
vrst[i] = vrst[x] + 1;
pd[x] += dfs(i, x);
par[x] += par[i];
}
if(g[x].size() == 1){
par[x]++;
}
par[x] = (par[x] - 1) % 2 + 1;
return pd[x];
}
void dfs2(int x, int pr = -1){
e[x] = ti; ti++;
for(int ii = 0; ii < g[x].size(); ii++){
int i = g[x][ii];
if(i == pr) continue;
if(ii == 0){
nxt[i] = nxt[x];
}
else nxt[i] = i;
dfs2(i, x);
}
return;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, q; cin >> n >> q;
pd.resize(n, 0);
vrst.resize(n);
e.resize(n);
o.resize(n, -1);
par.resize(n, 0);
nxt.resize(n);
g.resize(n);
For(i, n-1){
int a, b; cin >> a >> b; a--; b--;
g[a].push_back(b);
g[b].push_back(a);
}
vrst[0] = 0;
dfs(0);
For(i, n){
int mx = 0;
int mp = 0;
For(j, g[i].size()){
if(g[i][j] == o[i]) continue;
if(mx < pd[g[i][j]]) {
mp = j;
}
}
swap(g[i][0], g[i][mp]);
}
nxt[0] = 0;
dfs2(0);
intervalac seg(n);
int suc = 0;
int pl = par[0] % 2;
For(i, n){
seg.zmen(e[i], par[i]);
suc += par[i];
}
vec<int> ph(n, 0);
For(i, n){
ph[i] = g[i].size();
}
For(i, q){
pl = par[0];
int d; cin >> d;
int zm = 0;
vec<int> qq;
For(j, d){
int a; cin >> a; a--;
ph[a]++;
if(ph[a] == 2){
continue;
}
pl = 1 - pl;
qq.push_back(a);
while(a != -1){
zm += seg.daj(e[nxt[a]], e[a]);
a = o[nxt[a]];
}
}
if(pl == 1){
cout << -1 << endl;
}
else cout << suc + zm + d - 2 << endl;
For(j, qq.size()){
int a = qq[j];
ph[a]--;
while(a != -1){
seg.daj(e[nxt[a]], e[a]);
a = o[nxt[a]];
}
}
}
return 0;
}
