#include <bits/stdc++.h>
using namespace std;
#define eb emplace_back
struct edge {
int v, i;
edge(int v, int i): v(v), i(i) {}
};
const int N = 1e5 + 5;
const int LG = 17;
vector <edge> adj[N];
vector <int> path, ret;
int tin[N], tim, n, m, k;
int rmq[LG][N], lg[N], ss[N];
int st[N], tp, sp[N], d[N];
void dfs(int u, int p) {
tin[u] = tim++;
for (edge e : adj[u])
if (e.v != p) {
ret.eb(tin[u]); path.eb(u);
d[e.v] = d[u] + 1; dfs(e.v, u);
}
}
int lca(int u, int v) {
if (!u || !v) return u | v;
if (u == v) return u;
tie(u, v) = minmax(tin[u], tin[v]);
int k = lg[v - u];
return path[min(rmq[k][u],
rmq[k][v - (1 << k)])];
}
void add(int u, int r) {
ss[u]++; ss[r]--;
}
void init() {
dfs(1, 0);
for (int i = 0; i < n - 1; i++)
rmq[0][i] = ret[i];
for (int i = 2; i < n; i++)
lg[i] = lg[i / 2] + 1;
for (int x = 1; (1 << x) < n; x++)
for (int i = 0; i + (1 << x) < n; i++)
rmq[x][i] = min(rmq[x - 1][i],
rmq[x - 1][i + (1 << (x - 1))]);
}
void vis(int u, int p) {
for (edge e : adj[u])
if (e.v != p) {
vis(e.v, u); ss[u] += ss[e.v];
}
if (ss[u] >= k)
for (edge e : adj[u])
if (e.v == p) ret.eb(e.i);
}
void input() {
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
adj[u].eb(v, i); adj[v].eb(u, i);
}
}
void process() {
ret.clear();
for (int i = 0; i < m; i++) {
int s; cin >> s;
st[tp = 0] = 0;
for (int i = 0; i < s; i++) {
cin >> sp[i];
st[0] = lca(st[0], sp[i]);
}
//cout << st[0] << '\n';
for (int i = 0; i < s; i++) {
if (sp[i] == st[0]) continue;
int r = lca(st[tp], sp[i]);
while (tp && d[r] < d[st[tp - 1]]) {
add(st[tp], st[tp - 1]); tp--;
}
if (d[r] < d[st[tp]]) add(st[tp--], r);
if (st[tp] != r) st[++tp] = r;
st[++tp] = sp[i];
}
while (tp) {
add(st[tp], st[tp - 1]); tp--;
}
}
vis(1, 0);
}
void output() {
sort(ret.begin(), ret.end());
cout << ret.size() << '\n';
for (int i : ret)
cout << i << ' ';
}
int main() {
cin.tie(0)->sync_with_stdio(0);
input(); init(); process(); output();
}
