// CEOI 2020 - Spring Cleaning
// Lúcio Cardoso
// Solution is the same as in editorial (with HLD)
#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5+10;
int n, q;
vector<int> grafo[maxn];
struct SegmentTree
{
int tree[2][4*maxn], lazy[4*maxn];
void build(int node, int l, int r)
{
tree[0][node] = r-l+1;
if (l == r) return;
int mid = (l+r)>>1;
build(2*node, l, mid); build(2*node+1, mid+1, r);
}
void flush(int node, int l, int r)
{
if (!lazy[node]) return;
if (l != r) lazy[2*node] += lazy[node], lazy[2*node+1] += lazy[node];
if (abs(lazy[node])%2) swap(tree[0][node], tree[1][node]);
lazy[node] = 0;
}
void upd(int node, int l, int r, int a, int b, int v)
{
flush(node, l, r);
if (l > b || r < a) return;
if (l >= a && r <= b)
{
lazy[node] = v;
flush(node, l, r);
return;
}
int mid = (l+r)>>1;
upd(2*node, l, mid, a, b, v); upd(2*node+1, mid+1, r, a, b, v);
tree[0][node] = tree[0][2*node]+tree[0][2*node+1];
tree[1][node] = tree[1][2*node]+tree[1][2*node+1];
}
} seg;
struct HeavyLight
{
int pai[maxn], nivel[maxn], sub[maxn];
int head[maxn], chain[maxn], pos[maxn], cc, tt;
void init(void)
{
cc = 1;
}
void dfs(int u, int p)
{
sub[u] = 1;
for (auto v: grafo[u])
{
if (v == p) continue;
pai[v] = u, nivel[v] = nivel[u]+1;
dfs(v, u);
sub[u] += sub[v];
}
}
void hld(int u)
{
if (!head[cc]) head[cc] = u;
chain[u] = cc, pos[u] = ++tt;
int mx = 0, ind = -1;
for (auto v: grafo[u])
if (v != pai[u] && sub[v] > mx)
mx = sub[v], ind = v;
if (ind != -1) hld(ind);
for (auto v: grafo[u])
{
if (v != pai[u] && v != ind)
{
++cc;
hld(v);
}
}
}
void upd_path(int u, int v, int k)
{
while (true)
{
if (chain[u] == chain[v])
{
seg.upd(1, 1, n, pos[v], pos[u], k);
return;
}
seg.upd(1, 1, n, pos[head[chain[u]]], pos[u], k);
u = pai[head[chain[u]]];
}
}
} HLD;
int liga[maxn];
int main(void)
{
scanf("%d %d", &n, &q);
for (int i = 1; i < n; i++)
{
int u, v;
scanf("%d %d", &u, &v);
grafo[u].push_back(v);
grafo[v].push_back(u);
}
int r;
for (int i = 1; i <= n; i++)
if (grafo[i].size() != 1)
r = i;
seg.build(1, 1, n);
HLD.init(); HLD.dfs(r, 0); HLD.hld(r);
for (int i = 1; i <= n; i++)
if (grafo[i].size() == 1)
HLD.upd_path(i, r, 1);
int leaf = 0;
for (int i = 1; i <= n; i++)
if (grafo[i].size() == 1)
leaf++;
while (q--)
{
int d;
scanf("%d", &d);
int l = leaf+d;
vector<int> A;
set<int> B;
for (int i = 1; i <= d; i++)
{
int u;
scanf("%d", &u);
liga[d] = u;
HLD.upd_path(u, r, 1);
A.push_back(u);
B.insert(u);
}
for (auto v: B)
{
if (grafo[v].size() == 1)
{
l--;
HLD.upd_path(v, r, -1);
}
}
int ans = n+d-1;
seg.flush(1, 1, n);
ans += seg.tree[0][1]-1;
if (l%2) printf("-1\n");
else printf("%d\n", ans);
for (auto v: B)
if (grafo[v].size() == 1)
HLD.upd_path(v, r, 1);
for (auto v: A)
HLD.upd_path(v, r, -1);
}
}
