#include <bits/stdc++.h>
#define ll long long
#define task "crt"
using namespace std;
const int N = 2e5 + 16;
int n, q, u, v;
vector <int> adj[N];
ll result;
/*
7 3
1 2
2 4
4 5
5 6
5 7
3 4
1 4
2 2 4
1 1
*/
int leaves[N];
void preDfs(int k, int p) {
if (adj[k].size() == 1 && k != 1) {
leaves[k] = 1;
}
else {
leaves[k] = 0;
}
for (auto v : adj[k]) {
if (v == p) {
continue;
}
preDfs(v, k);
leaves[k] += leaves[v];
}
if (leaves[k] & 1) {
leaves[k] = 1;
}
else {
leaves[k] = 2;
}
}
int h[N], par[N], sz[N];
int chainHead[N], chainId[N], chainArr[N], pos[N], curPos = 1, curChain = 1, endPos[N];
void dfs(int k, int p) {
sz[k] = 1;
for (auto v : adj[k]) {
if (v == p) {
continue;
}
h[v] = h[k] + 1;
par[v] = k;
dfs(v, k);
sz[k] += sz[v];
}
}
void hld(int k, int p) {
if (!chainHead[curChain]) {
chainHead[curChain] = k;
}
chainId[k] = curChain;
pos[k] = curPos;
chainArr[curPos] = k;
curPos++;
int heaviest = 0;
for (auto v : adj[k]) {
if (v == p) {
continue;
}
if (heaviest == 0 || sz[v] > sz[heaviest]) {
heaviest = v;
}
}
if (heaviest) {
hld(heaviest, k);
}
for (auto v : adj[k]) {
if (v == p || v == heaviest) {
continue;
}
curChain++;
hld(v, k);
}
endPos[k] = curPos - 1;
}
int lca(int u, int v) {
while (chainId[u] != chainId[v]) {
if (chainId[u] > chainId[v]) {
u = par[chainHead[chainId[u]]];
}
else {
v = par[chainHead[chainId[v]]];
}
}
if (h[u] < h[v]) {
return u;
}
return v;
}
struct node {
int val = 0, lazy = 0;
node operator + (const node &other) const {
node ans;
ans.val = val + other.val;
return ans;
}
};
node segmentTree[N << 2];
void build(int k, int l, int r) {
if (l == r) {
segmentTree[k].val = (leaves[chainArr[l]] == 2);
return;
}
int mid = l + r >> 1;
build(k << 1, l, mid);
build(k << 1 | 1, mid + 1, r);
segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}
void down(int k, int l, int r) {
if (segmentTree[k].lazy) {
int mid = l + r >> 1;
segmentTree[k << 1].val = (mid - l + 1) - segmentTree[k << 1].val;
segmentTree[k << 1].lazy ^= 1;
segmentTree[k << 1 | 1].val = (r - mid) - segmentTree[k << 1 | 1].val;
segmentTree[k << 1 | 1].lazy ^= 1;
segmentTree[k].lazy ^= 1;
}
}
void update(int k, int l, int r, int x, int y) {
if (l > y || x > r) {
return;
}
if (l >= x && r <= y) {
segmentTree[k].val = (r - l + 1) - segmentTree[k].val;
segmentTree[k].lazy ^= 1;
return;
}
int mid = l + r >> 1;
down(k, l, r);
update(k << 1, l, mid, x, y);
update(k << 1 | 1, mid + 1, r, x, y);
segmentTree[k] = segmentTree[k << 1] + segmentTree[k << 1 | 1];
}
void updateTree(int u, int v) {
int LCA = lca(u, v);
while (chainId[u] != chainId[LCA]) {
update(1, 1, curPos, pos[chainHead[chainId[u]]], pos[u]);
u = par[chainHead[chainId[u]]];
}
while (chainId[v] != chainId[LCA]) {
update(1, 1, curPos, pos[chainHead[chainId[v]]], pos[v]);
v = par[chainHead[chainId[v]]];
}
if (h[u] < h[v]) {
update(1, 1, curPos, pos[u] + 1, pos[v]);
}
else {
update(1, 1, curPos, pos[v] + 1, pos[u]);
}
}
int deg[N], cnt[N], initialLeaves, isLeaf[N];
int main() {
ios_base :: sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin >> n >> q;
for (int i = 1; i < n; i++) {
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; i++) {
deg[i] = adj[i].size();
if (deg[i] <= 1) {
initialLeaves++;
isLeaf[i] = true;
}
}
preDfs(1, 1);
dfs(1, 1);
hld(1, 1);
leaves[1] = 0;
build(1, 1, curPos);
while (q--) {
int d;
cin >> d;
int curLeaves = initialLeaves;
vector <int> query;
for (int i = 1; i <= d; i++) {
cin >> u;
if (deg[u] <= 1) {
curLeaves--;
}
curLeaves++;
cnt[u]++;
deg[u]++;
query.push_back(u);
}
sort(query.begin(), query.end());
query.erase(unique(query.begin(), query.end()), query.end());
if (curLeaves & 1) {
cout << -1 << "\n";
for (auto x : query) {
deg[x] = adj[x].size();
cnt[x] = 0;
}
continue;
}
for (auto x : query) {
if (isLeaf[x] && ((cnt[x] & 1) == 0)) {
updateTree(1, x);
}
else if (!isLeaf[x] && ((cnt[x] & 1) == 1)) {
updateTree(1, x);
}
}
cout << n - 1 + d + segmentTree[1].val << "\n";
for (auto x : query) {
if (isLeaf[x] && ((cnt[x] & 1) == 0)) {
updateTree(1, x);
}
else if (!isLeaf[x] && ((cnt[x] & 1) == 1)) {
updateTree(1, x);
}
}
for (auto x : query) {
deg[x] = adj[x].size();
cnt[x] = 0;
}
}
return 0;
}
