#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define fr first
#define sc second
const int N = 1e5 + 5;
vector<int> vec[N];
int root, sz[N], heavyHead[N], tata[N], posHeavy[N], heavy[N], p;
int leavesSubarb[N], isLeaf[N], lastScos[N], n;
void dfs1(int nod, int papa) {
sz[nod] = 1;
tata[nod] = papa;
for (auto i : vec[nod])
if (i != papa) {
dfs1(i, nod);
sz[nod] += sz[i];
leavesSubarb[nod] += leavesSubarb[i];
}
if (leavesSubarb[nod] == 0) {
leavesSubarb[nod] ++;
isLeaf[nod] = 1;
}
}
void dfs2(int nod, int papa) {
posHeavy[nod] = ++ p;
heavy[p] = nod;
sort(vec[nod].begin(), vec[nod].end(), [&](int a, int b) {return sz[a] > sz[b];});
int hh = 0;
for (auto i : vec[nod])
if (i != papa) {
if (!hh) {
heavyHead[i] = heavyHead[nod];
hh = 1;
} else {
heavyHead[i] = i;
}
dfs2(i, nod);
}
}
pii aint[4 * N];
int lazy[4 * N];
pii join(pii a, pii b) {
return {a.fr + b.fr, a.sc + b.sc};
}
void build(int pos, int l, int r) {
aint[pos] = {0, r - l + 1};
if (l != r) {
build (2 * pos, l, (l + r) >> 1);
build (2 * pos + 1, ((l + r) >> 1) + 1, r);
}
}
void propag(int pos) {
if (lazy[pos] == 0)
return;
aint[pos].fr = aint[pos].sc - aint[pos].fr;
if (2 * pos + 1 < 4 * N) {
lazy[2 * pos] ^= 1;
lazy[2 * pos + 1] ^= 1;
}
lazy[pos] = 0;
}
void update(int pos, int st, int dr, int l, int r) {
propag(pos);
if (l <= st && dr <= r) {
lazy[pos] ^= 1;
propag(pos);
return;
}
int mid = (st + dr) >> 1;
if (l <= mid)
update(2 * pos, st, mid, l, r);
else
propag(2 * pos);
if (mid < r)
update(2 * pos + 1, mid + 1, dr, l, r);
else
propag(2 * pos + 1);
aint[pos] = join(aint[2 * pos], aint[2 * pos + 1]);
}
pii query(int pos, int st, int dr, int l, int r) {
propag(pos);
if (l <= st && dr <= r)
return aint[pos];
int mid = (st + dr) >> 1;
if (r <= mid)
return query(2 * pos, st, mid, l, r);
if (mid < l)
return query(2 * pos + 1, mid + 1, dr, l, r);
return join(query(2 * pos, st, mid, l, r), query(2 * pos + 1, mid + 1, dr, l, r));
}
void updateUp(int nod) {
if (nod == 0)
return;
update(1, 1, n, posHeavy[heavyHead[nod]], posHeavy[nod]);
updateUp(tata[heavyHead[nod]]);
}
int main() {
int q;
cin >> n >> q;
for (int i = 1; i < n; i ++) {
int x, y;
cin >> x >> y;
vec[x].push_back(y);
vec[y].push_back(x);
}
int leaves = 0;
for (int i = 1; i <= n; i ++) {
if (vec[i].size() > 1)
root = i;
else
leaves ++;
}
dfs1(root, 0);
heavyHead[root] = root;
dfs2(root, 0);
build(1, 1, n);
for (int i = 1; i <= n; i ++)
if (leavesSubarb[heavy[i]] % 2 == 0)
update(1, 1, n, i, i);
for (int id = 1; id <= q; id ++) {
int d;
cin >> d;
vector<int> a;
int newLeaves = 0;
for (int i = 0; i < d; i ++) {
int x;
cin >> x;
a.push_back(x);
updateUp(x);
newLeaves ++;
if (isLeaf[x] && lastScos[x] < id) {
lastScos[x] = id;
updateUp(x);
newLeaves --;
}
}
if (newLeaves % 2 == 0)
cout << n - 1 + d + query(1, 1, n, 2, n).fr << '\n';
else
cout << "-1\n";
for (auto x : a) {
updateUp(x);
if (isLeaf[x] && lastScos[x] == id) {
lastScos[x] = 0;
updateUp(x);
}
}
}
}
