#include "bits/stdc++.h"
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif
using ll = long long;
using pii = pair<int, int>;
#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
assert(l <= r);
return uniform_int_distribution<ll> (l, r)(rng);
}
const int N = 1e5 + 3;
int n, q, root;
vector<int> g[N];
int leaf[N];
bool is_leaf[N];
int pos[N], p[N], head[N], cur_pos, h[N], sz[N];
namespace ST{
int st[N << 2], lz[N << 2];
void flip_node(int id, int l, int r){
lz[id] ^= 1;
st[id] = (r - l + 1) - st[id];
}
void down(int id, int l, int r){
int mid = (l + r) >> 1;
flip_node(id << 1, l, mid);
flip_node(id << 1 | 1, mid + 1, r);
lz[id] = 0;
}
void update(int pos, int val, int id = 1, int l = 1, int r = n){
if(l == r){
st[id] = val;
return;
}
int mid = (l + r) >> 1;
if(pos <= mid)
update(pos, val, id << 1, l, mid);
else
update(pos, val, id << 1 | 1, mid + 1, r);
st[id] = st[id << 1] + st[id << 1 | 1];
}
void flip(int tl, int tr, int id = 1, int l = 1, int r = n){
if(l > tr or tl > r)
return;
if(tl <= l and r <= tr){
flip_node(id, l, r);
return;
}
int mid = (l + r) >> 1;
if(lz[id])
down(id, l, r);
flip(tl, tr, id << 1, l, mid);
flip(tl, tr, id << 1 | 1, mid + 1, r);
st[id] = st[id << 1] + st[id << 1 | 1];
}
}
void dfs(int u, int pre = -1){
is_leaf[u] = (sz(g[u]) == 1);
leaf[u] = is_leaf[u];
sz[u] = 1;
for(int v : g[u]){
if(v == pre)
continue;
h[v] = h[u] + 1;
p[v] = u;
dfs(v, u);
sz[u] += sz[v];
leaf[u] += leaf[v];
}
}
void hld(int u, int cur_head, int pre = -1){
pos[u] = ++cur_pos;
head[u] = cur_head;
int nx = -1;
for(int v : g[u])
if(v != pre and (nx == -1 or sz[nx] < sz[v]))
nx = v;
if(nx != -1)
hld(nx, cur_head, u);
for(int v : g[u])
if(v != pre and v != nx)
hld(v, v, u);
}
void flip(int u){
while(head[u] != root){
ST::flip(pos[head[u]], pos[u]);
u = p[head[u]];
}
ST::flip(2, pos[u]);
}
void solve(){
cin >> n >> q;
for(int i = 1; i < n; ++i){
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
for(int i = 1; i <= n; ++i){
if(sz(g[i]) > 1){
root = i;
break;
}
}
dfs(root);
hld(root, root);
for(int i = 1; i <= n; ++i)
if(i != root)
ST::update(pos[i], leaf[i] % 2 == 0);
while(q--){
int d;
cin >> d;
int cnt = leaf[root] + d;
vector<int> old_leaf, changed;
for(int i = 1; i <= d; ++i){
int a;
cin >> a;
if(is_leaf[a]){
is_leaf[a] = 0, --cnt;
old_leaf.push_back(a);
}
else{
changed.push_back(a);
flip(a);
}
}
if(cnt & 1)
cout << -1 << '\n';
else
cout << n - 1 + d + ST::st[1] << '\n';
for(int i : old_leaf)
is_leaf[i] = 1;
for(int i : changed)
flip(i);
}
}
int32_t main() {
cin.tie(nullptr)->sync_with_stdio(0);
#define task "troll"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int test = 1;
// cin >> test;
for(int i = 1; i <= test; ++i){
// cout << "Case #" << i << ": ";
solve();
}
#ifdef LOCAL
cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
#endif
return 0;
}
