///huynhocute123///
#include<bits/stdc++.h>
using namespace std;
#define S second
#define F first
#define pii pair<int,int>
#define piii pair<int,pair<int,int>>
#define pb push_back
#define FOR(i, a, b) for(int i = a; i <= b; ++i)
#define REP(i, a, b) for(int i = b; i >= a; --i)
#define ALL(v) v.begin(),v.end()
#define inp(name) if(fopen(name, "r")) freopen(name, "r", stdin);
#define out(name) if(fopen(name, "w")) freopen(name, "w", stdout);
//random_device rd;
//mt19937 rng(rd());
//#pragma GCC optimize ("O3")
//#pragma GCC optimize ("unroll-loops")
//#pragma GCC target("popcnt")
//#define int long long
const int MAX = 1e9+9;
const long long MAXLL = 1e18+9;
const double pi = 3.14159265358979323846;
const double rad = 3.14159265358979323846 /180;
bool minimize(int &u, int v){
if(v < u){
u = v;
return 1;
}
return 0;
}
bool maximize(int &u, int v){
if(v > u){
u = v;
return 1;
}
return 0;
}
bool maximizell(long long &u, long long v){
if(v > u){
u = v;
return 1;
}
return 0;
}
bool minimizell(long long &u, long long v){
if(v < u){
u = v;
return 1;
}
return 0;
}
const int mod = 1e9 + 7;
inline int fastPow(int a, int n){
if(n == 0) return 1;
int t = fastPow(a, n >> 1);
t = 1ll * t * t % mod;
if(n & 1) t = 1ll * t * a % mod;
return t;
}
const int maxN = 1e5 + 99 ;
int n, q;
vector<int> e[maxN];
bool leaf[maxN], ok[maxN];
int sz[maxN] ,par[maxN];
int head[maxN] , chain[maxN] , pos[maxN] , ar[maxN], c_chain, c_pos;
int Count_leaf[maxN];
void pre(int u ,int p){
// cout << u << '\n';
sz[u] = 1;
for(auto x : e[u]){
if(x == p)continue;
par[x] = u;
pre(x ,u);
sz[u] = sz[u] + sz[x];
Count_leaf[u] += Count_leaf[x];
}
if(e[u].size() == 1){
Count_leaf[u]++;
leaf[u] = 1;
ok[u] = 1;
}
}
void hld(int u ,int p){
if(!head[c_chain])head[c_chain] = u;
chain[u] = c_chain;
pos[u] = ++c_pos;
ar[c_pos] = u;
int nxt = 0;
for(auto x : e[u]){
if(x == p)continue;
if(nxt == 0 || sz[x] > sz[nxt])nxt = x;
}
if(nxt)hld(nxt, u);
for(auto x : e[u]){
if(x == p || x == nxt)continue;
++c_chain;
hld(x, u);
}
}
pii st[4 * maxN];
int lazy[4 * maxN];
void push(int id){
if(lazy[id] == 0)return;
st[id << 1].F = st[id << 1].S - st[id << 1].F;
st[id << 1 | 1].F = st[id << 1 | 1].S - st[id << 1 | 1].F;
lazy[id << 1] ^= 1;
lazy[id << 1 | 1] ^= 1;
lazy[id] = 0;
}
pii Merge(pii X , pii Y){
return make_pair(X.F + Y.F , X.S + Y.S);
}
void build(int id, int l ,int r){
if(l == r){
st[id] = make_pair( (Count_leaf[ar[l]] & 1 ) ? 1 : 2 , 3);
// cerr << l << " " << ar[l] << " " <<Count_leaf[ar[l]] <<" " << st[id].F << '\n';
return;
}
int mid = (l + r)/2;
build(id << 1, l ,mid);
build(id << 1 | 1,mid + 1, r);
st[id] = Merge(st[id << 1] ,st[id << 1 | 1]);
}
void upd(int id ,int l ,int r ,int u ,int v){
if(v < l || u > r)return;
if(u <= l && r <= v){
st[id].F = st[id].S - st[id].F;
lazy[id] ^= 1;
return;
}
int mid = (l +r)/2;
push(id);
upd(id << 1, l ,mid , u ,v);
upd(id << 1 | 1,mid + 1, r , u ,v);
st[id] = Merge(st[id << 1 ] ,st[id << 1 | 1]);
}
pii get(int id, int l ,int r ,int u,int v){
if(v < l || u > r)return make_pair(0 , 0);
if(u <= l && r <= v)return st[id];
int mid = (l + r)/2;
push(id);
return Merge(get(id << 1 ,l , mid , u ,v) , get(id << 1 | 1, mid + 1, r, u , v));
}
int path_upd(int u ,int v){
int delta = 0;
while(1){
if(chain[u] != chain[v]){
if(chain[u] < chain[v])swap(u ,v);
int top = head[chain[u]];
pii X = get(1, 1, n , pos[top], pos[u]);
// cout << X.F << " " << X.S << '\n';
delta += -2 * X.F + X.S;
upd(1, 1, n , pos[top], pos[u]);
u = par[top];
}else{
int l = min(pos[u] , pos[v]);
int r = max(pos[u] , pos[v]);
pii X = get(1, 1, n , l + 1, r );
// cout << X.F << " " << X.S << '\n';
delta += -2 * X.F + X.S;
upd(1, 1, n , l + 1, r);
break;
}
}
// cout << delta << " ";
return delta;
}
inline void solve(){
cin >> n >> q;
FOR(i, 2 ,n){
int u ,v ;cin >> u >> v;
e[u].pb(v);
e[v].pb(u);
}
pre(1, 0);
c_chain = 1;
c_pos = 0;
hld(1, 0);
build(1, 1 ,n);
// cout << path_upd(4, 1);
FOR(xccx ,1 , q){
vector<int> ar;
int sz;cin >> sz;
FOR(i, 1 ,sz){
int x; cin >> x;
ar.pb(x);
}
int cur_leaf = Count_leaf[1];
for(auto x : ar){
if(leaf[x] == 0)++cur_leaf;
else{
if(ok[x])ok[x] = 0;
else ++cur_leaf;
}
}
for(auto x : ar)ok[x] = 1;
if(cur_leaf & 1){
cout << -1 << '\n';
continue;
}
int cur_ans = get(1, 1, n, 2, n).F;
vector<int> change;
for(auto x : ar){
if(leaf[x]){
if(ok[x])ok[x] = 0;
else{
change.pb(x);
cur_ans += path_upd(x , 1);
}
}else {
change.pb(x);
cur_ans += path_upd(x , 1);
}
}
for(auto x : change)path_upd(x ,1);
cout << cur_ans + sz << '\n';
cerr << cur_ans + sz << '\n';
for(auto x : ar)ok[x] = 1;
// cout << get(1, 1, n, 2, n).F << '\n';
}
// cout << get(1, 1, n , pos[6] ,pos[6]) <<'\n';
// cout << get(1, 1, n ,2 , n) << '\n';
// cout << st[1].F;
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
#define NAME "task"
if(fopen(NAME".inp", "r")){
freopen(NAME".inp", "r" ,stdin);
freopen(NAME".out", "w" ,stdout);
}
int tc = 1;
// cin >> tc;
while( tc-- )solve();
cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" ;
}
