#include <bits/stdc++.h>
#define ll long long
#define task "crt"
using namespace std;
const int N = 200000 + 16;
int n, q, u, v, a[N];
vector<int> adj[N];
ll result;
int leaves[N];
void preDfs(int k, int p) {
if (adj[k].size() == 1) leaves[k] = 1;
else leaves[k] = 0;
for (auto to : adj[k]) {
if (to == p) continue;
preDfs(to, k);
leaves[k] += leaves[to];
}
}
/* HLD */
int h[N], sz[N], par[N];
int chainId[N], chainArr[N], pos[N], chainHead[N], curPos = 1, curChain = 1, endPos[N];
int SZ; // số lượng vị trí hợp lệ sau HLD
void dfs(int k, int p) {
sz[k] = 1;
par[k] = p;
for (auto to : adj[k]) {
if (to == p) continue;
h[to] = h[k] + 1;
dfs(to, k);
sz[k] += sz[to];
}
}
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 to : adj[k]) {
if (to == p) continue;
if (heaviest == 0 || sz[to] > sz[heaviest]) heaviest = to;
}
if (heaviest) hld(heaviest, k);
for (auto to : adj[k]) {
if (to == p || to == heaviest) continue;
curChain++;
hld(to, k);
}
endPos[k] = curPos - 1;
}
int lca(int u, int v) {
// So sánh bằng đầu chuỗi theo độ sâu head (KHÔNG dùng chainId trực tiếp)
while (chainHead[chainId[u]] != chainHead[chainId[v]]) {
if (h[chainHead[chainId[u]]] > h[chainHead[chainId[v]]]) {
u = par[chainHead[chainId[u]]];
} else {
v = par[chainHead[chainId[v]]];
}
}
return (h[u] < h[v]) ? u : 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) {
if (l <= SZ && leaves[chainArr[l]] & 1) segmentTree[k].val = 1;
else segmentTree[k].val = 0;
segmentTree[k].lazy = 0;
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];
segmentTree[k].lazy = 0;
}
void down(int k, int l, int r) {
if (!segmentTree[k].lazy) return;
int mid = (l + r) >> 1;
// flip left child
segmentTree[k << 1].val = (mid - l + 1) - segmentTree[k << 1].val;
segmentTree[k << 1].lazy ^= 1;
// flip right child
segmentTree[k << 1 | 1].val = (r - mid) - segmentTree[k << 1 | 1].val;
segmentTree[k << 1 | 1].lazy ^= 1;
segmentTree[k].lazy = 0;
}
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];
}
node getSeg(int k, int l, int r, int x, int y) {
if (l > y || x > r) {
return node();
}
if (l >= x && r <= y) return segmentTree[k];
int mid = (l + r) >> 1;
down(k, l, r);
return getSeg(k << 1, l, mid, x, y) + getSeg(k << 1 | 1, mid + 1, r, x, y);
}
void updateTree(int u, int v) {
int L = lca(u, v);
while (chainId[u] != chainId[L]) {
update(1, 1, SZ, pos[chainHead[chainId[u]]], pos[u]);
u = par[chainHead[chainId[u]]];
}
while (chainId[v] != chainId[L]) {
update(1, 1, SZ, pos[chainHead[chainId[v]]], pos[v]);
v = par[chainHead[chainId[v]]];
}
if (h[u] < h[v]) update(1, 1, SZ, pos[u], pos[v]);
else update(1, 1, SZ, pos[v], pos[u]);
}
node getTree(int u, int v) {
node ans;
int L = lca(u, v);
while (chainId[u] != chainId[L]) {
ans = getSeg(1, 1, SZ, pos[chainHead[chainId[u]]], pos[u]) + ans;
u = par[chainHead[chainId[u]]];
}
while (chainId[v] != chainId[L]) {
ans = getSeg(1, 1, SZ, pos[chainHead[chainId[v]]], pos[v]) + ans;
v = par[chainHead[chainId[v]]];
}
if (h[u] < h[v]) ans = getSeg(1, 1, SZ, pos[u], pos[v]) + ans;
else ans = getSeg(1, 1, SZ, pos[v], pos[u]) + ans;
return ans;
}
node getSubtree(int u) {
return getSeg(1, 1, SZ, pos[u], endPos[u]);
}
int leafCnt;
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
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);
}
preDfs(1, 1);
// chuẩn bị HLD
h[1] = 0;
par[1] = 1;
dfs(1, 1);
hld(1, 1);
SZ = curPos - 1; // số vị trí thực sự dùng (1..SZ)
build(1, 1, SZ);
for (int i = 1; i <= n; i++) if (adj[i].size() == 1) leafCnt++;
while (q--) {
int d; cin >> d;
for (int i = 1; i <= d; i++) cin >> a[i];
set<int> distinct;
for (int i = 1; i <= d; i++) {
updateTree(1, a[i]); // toggle path 1..a[i]
if (adj[a[i]].size() == 1) distinct.insert(a[i]);
}
if ((leafCnt - (int)distinct.size() + d) & 1) {
result = -1;
} else {
ll oddAll = getSubtree(1).val + d; // số node có odd (bao gồm n+i)
ll evenSum = 2LL * (n + d - oddAll);
result = oddAll + evenSum; // = 2*(n+d) - oddAll
// chuyển về công thức đúng (loại node 1 khỏi tổng theo công thức gốc)
if (getTree(1, 1).val == 1) result -= 1;
else result -= 2;
}
cout << result << '\n';
// rollback (toggle lại)
for (int i = 1; i <= d; i++) updateTree(1, a[i]);
}
return 0;
}
