// author : Nguyễn Trọng Nguyễn - ITK22 NBK
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ii pair <int, int>
#define fi first
#define sc second
const int maxn = (int)1e5;
const int inf = (int)1e9;
const int LG = 16;
int n, m, k;
vector <int> adj[maxn + 5];
ii edge[maxn + 5];
int timer = 0;
int up[LG + 5][maxn + 5], tin[maxn + 5], tout[maxn + 5];
int sz[maxn + 5], npos = 0, nchain = 0;
int apos[maxn + 5], chains[maxn + 5], head[maxn + 5];
int st[maxn * 4 + 5], lazy[maxn * 4 + 5], cnt[maxn + 5];
void dfs (int u = 1, int p = 1) {
tin[u] = ++timer;
sz[u] = 1;
up[0][u] = p;
for (int e = 1; e <= LG; e++)
up[e][u] = up[e - 1][up[e - 1][u]];
for (auto v : adj[u]) {
if (v == p) continue;
dfs(v, u);
sz[u] += sz[v];
}
tout[u] = timer;
}
bool isAncestor (int u, int v) {
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca (int u, int v) {
if (isAncestor(u, v)) return u;
if (isAncestor(v, u)) return v;
for (int exp = LG; exp >= 0; exp--)
if (!isAncestor(up[exp][u], v))
u = up[exp][u];
return up[0][u];
}
void hld (int u = 1, int p = 1) {
if (head[nchain] == 0) head[nchain] = u;
chains[u] = nchain;
apos[u] = ++npos;
int hv = -1;
for (auto v : adj[u]) {
if (v == p) continue;
if (hv == -1 or sz[hv] < sz[v])
hv = v;
}
if (hv != -1) hld(hv, u);
for (int v : adj[u]) {
if (v == p or v == hv) continue;
nchain++;
hld(v, u);
}
}
void down (int id, int l, int mid, int r) {
if (lazy[id] == 0) return ;
int &v = lazy[id];
st[id << 1] += (mid - l + 1) * v;
st[id << 1 | 1] += (r - mid) * v;
lazy[id << 1] += v;
lazy[id << 1 | 1] += v;
v = 0;
}
void update (int id, int l, int r, int u, int v, int val) {
if (v < l or r < u) return ;
if (u <= l and r <= v) {
st[id] += (r - l + 1) * val;
lazy[id] += val;
return ;
}
int mid = l + r >> 1;
down(id, l, mid, r);
update(id << 1, l, mid, u, v, val);
update(id << 1 | 1, mid + 1, r, u, v, val);
st[id] = st[id << 1] + st[id << 1 | 1];
}
int get (int id, int l, int r, int u) {
if (u < l or r < u) return 0;
if (l == r) return st[id];
int mid = l + r >> 1;
down(id, l, mid, r);
return get(id << 1, l, mid, u) + get(id << 1 | 1, mid + 1, r, u);
}
void QUERY_UPDATE (int u, int _lca, int val) {
while (true) {
if (chains[u] == chains[_lca]) {
update(1, 1, n, apos[_lca], apos[u], val);
return ;
}
update(1, 1, n, apos[head[chains[u]]], apos[u], val);
u = up[0][head[chains[u]]];
}
}
int QUERY_GET (int u) {
return get(1, 1, n, u);
}
void init () {
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
edge[i] = {u, v};
}
}
bool cmp (int u, int v) {
return tin[u] < tin[v];
}
void process () {
dfs();
hld();
while (m--) {
vector <int> fix;
int x; cin >> x;
while (x--) {
int u; cin >> u;
fix.push_back(u);
}
sort(fix.begin(), fix.end(), cmp);
int cur = fix[0];
for (auto v : fix) {
int _lca = lca(v, cur);
QUERY_UPDATE(v, _lca, 1);
QUERY_UPDATE(_lca, _lca, -1);
cur = v;
}
}
vector <int> node;
for (int i = 1; i < n; i++) {
int u, v; tie(u, v) = edge[i];
int ans = up[0][u] == v ? QUERY_GET(u) : QUERY_GET(v);
if (ans >= k) node.push_back(i);
}
cout << (int)node.size() << '\n';
for (int v : node) cout << v << ' ';
}
signed main () {
cin.tie(0)->sync_with_stdio(false);
init();
process();
return 0;
}
