#include<bits/stdc++.h>
#define ll long long
#define task ""
using namespace std;
const int maxn = 1e5 + 1;
int n, q, u, v, deg[maxn], r, dp[maxn], D, a[maxn], b[maxn], tot;
int par[maxn], sz[maxn], nxt[maxn], id[maxn], re[maxn], chain[maxn], head[maxn], cc = 1, ct = 0;
vector<int> adj[maxn];
bool ok[maxn];
struct Node
{
int cnt[2];
bool lazy;
}st[4*maxn];
void dfs (int u, int p)
{
par[u] = p;
sz[u] = 1;
for (int v : adj[u])
{
if (v == p) continue;
dfs(v, u);
sz[u] += sz[v];
if (sz[v] > sz[nxt[u]]) nxt[u] = v;
dp[u] += dp[v];
}
if (sz[u] == 1) dp[u] = 1;
}
void hld (int u, int p)
{
if (head[cc] == 0) head[cc] = u;
chain[u] = cc;
id[u] = ++ct;
re[ct] = u;
if (nxt[u] != 0) hld(nxt[u], u);
for (int v : adj[u])
{
if (v == p || v == nxt[u]) continue;
cc++;
hld(v, u);
}
}
void build (int node, int l, int r)
{
if (l == r)
{
st[node].cnt[dp[re[l]] & 1] = 1;
st[node].lazy = false;
return;
}
int m = (l + r)/2;
build(2*node, l, m);
build(2*node + 1, m + 1, r);
st[node].cnt[0] = st[2*node].cnt[0] + st[2*node + 1].cnt[0];
st[node].cnt[1] = st[2*node].cnt[1] + st[2*node + 1].cnt[1];
}
void down (int node)
{
if (!st[node].lazy) return;
swap(st[2*node].cnt[0], st[2*node].cnt[1]);
swap(st[2*node + 1].cnt[0], st[2*node + 1].cnt[1]);
st[2*node].lazy ^= 1;
st[2*node + 1].lazy ^= 1;
st[node].lazy = false;
}
void upd (int node, int l, int r, int cl, int cr)
{
if (cr < l || r < cl) return;
if (cl <= l && r <= cr)
{
swap(st[node].cnt[0], st[node].cnt[1]);
st[node].lazy ^= 1;
return;
}
down(node);
int m = (l + r)/2;
upd(2*node, l, m, cl, cr);
upd(2*node + 1, m + 1, r, cl, cr);
st[node].cnt[0] = st[2*node].cnt[0] + st[2*node + 1].cnt[0];
st[node].cnt[1] = st[2*node].cnt[1] + st[2*node + 1].cnt[1];
}
void update (int u)
{
while (u != 0)
{
upd(1, 1, n, id[head[chain[u]]], id[u]);
u = par[head[chain[u]]];
}
}
void test (int node, int l, int r)
{
if (l == r)
{
cout << re[l] << ':';
if (st[node].cnt[0]) cout << 0 << " ";
else cout << 1 << " ";
return;
}
down(node);
int m = (l + r)/2;
test(2*node, l, m);
test(2*node + 1, m + 1, r);
}
int main()
{
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> q;
for (int i = 1; i < n; i++)
{
cin >> u >> v;
deg[u]++; deg[v]++;
adj[u].push_back(v);
adj[v].push_back(u);
}
for (int i = 1; i <= n; i++)
if (deg[i] > 1) r = i;
dfs(r, 0);
hld(r, 0);
/*for (int i = 1; i <= n; i++) cout << dp[i] << " ";
cout << '\n';
for (int i = 1; i <= n; i++) cout << id[i] << " ";
cout << '\n';
for (int i = 1; i <= n; i++) cout << re[i] << " ";
cout << '\n';*/
build(1, 1, n);
while (q--)
{
tot = dp[r];
cin >> D;
for (int i = 1; i <= D; i++)
{
cin >> a[i];
b[a[i]]++;
}
for (int i = 1; i <= D; i++)
{
if (ok[a[i]]) continue;
ok[a[i]] = true;
if (deg[a[i]] == 1)
{
tot += b[a[i]] - 1;
if (1 ^ (b[a[i]] & 1)) update(a[i]);
}
else
{
tot += b[a[i]];
if (b[a[i]] & 1) update(a[i]);
}
}
//cout << st[1].cnt[0] << " ";
if (tot & 1) cout << -1 << '\n';
else cout << n + D + st[1].cnt[0] - 2 << '\n';
//test(1, 1, n);
//cout << '\n';
for (int i = 1; i <= D; i++)
{
if (!ok[a[i]]) continue;
ok[a[i]] = false;
if (deg[a[i]] == 1)
{
if (1 ^ (b[a[i]] & 1)) update(a[i]);
}
else
{
if (b[a[i]] & 1) update(a[i]);
}
b[a[i]] = 0;
}
//test(1, 1, n);
//cout << '\n';
}
}
