// https://oj.uz/problem/view/BOI17_railway
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define tiii tuple<int,int,int>
#define vi vector<ll>
#define vvi vector<vi>
#define vpii vector<pii>
#define vtiii vector<tiii>
void dfs(vvi & adj, int v, int p, vi & in, vi & out, vvi & vorg, int & cnt, vi & depth, int d) {
in[v] = cnt++;
vorg[v].push_back(p); // erster vorg
for (int i = 1; 1 << (i-1) < vorg.size(); i++) {
vorg[v].push_back(vorg[vorg[v][i-1]][i-1]);
}
depth[v] = d;
for (int u : adj[v]) {
if (u == p) continue;
dfs(adj, u, v, in, out, vorg, cnt, depth, d+1);
}
out[v] = cnt++;
}
void dfs2(vvi & adj, int v, int p, vi & in, vi & out, vi & summe, vpii & edges, int k) {
int d = summe[in[v]] - summe[out[v]];
if (d >= k) {
if (v > p) edges.push_back({ p, v });
else edges.push_back({ v, p });
}
for (int u : adj[v]) {
if (u == p) continue;
dfs2(adj, u, v, in, out, summe, edges, k);
}
}
int lift(vvi & vorg, int a, int k) {
if (k == 0) return a;
int i = floor(log2(k));
return lift(vorg, vorg[a][i], k - (1 << i));
}
int lca(vvi & vorg, vi & depth, int a, int b) {
if (depth[a] < depth[b]) swap(a, b);
a = lift(vorg, a, depth[a] - depth[b]);
int low = 0; int up = depth[b];
for (int mid = (up + low)/2; low < up; mid = (up + low)/2) {
if (lift(vorg, a, mid) == lift(vorg, b, mid)) // gemeinsamer Vorgänger
up = mid;
else low = mid + 1;
}
return lift(vorg, b, low);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
map<pii, int> mapping;
int n,m,k;
cin >> n >> m >> k;
vvi adj(n);
for (int i = 1,a,b; i < n; i++) {
cin >> a >> b;
a--; b--;
adj[a].push_back(b);
adj[b].push_back(a);
if (a > b) swap(a,b);
mapping[make_pair(a,b)] = i;
}
// root = 0;
vi in(n);
vi out(n);
vi depth(n);
vvi vorg(n);
int cnt = 0;
dfs(adj, 0, 0, in, out, vorg, cnt, depth, 0);
vi pref(2 * n);
for (int i = 0,s; i < m; i++) {
cin >> s;
vpii neighbors(s);
for (int j = 0,l; j < s; j++) {
cin >> l; l--;
neighbors[j] = make_pair( in[l], l );
}
sort(neighbors.begin(), neighbors.end());
int current_lca = neighbors[0].second; // der lca aller bisher betrachteten Knoten
for (int j = 1; j < s; j++) {
int v = neighbors[j-1].second;
int u = neighbors[j].second;
int l = lca(vorg,depth,v,u);
if (in[l] < in[current_lca]) {
// hier ist der current lca unter dem aktuellen lca
pref[in[l]+1]++;
pref[in[current_lca]+1]--;
pref[in[l]+1]++;
pref[in[u]+1]--;
current_lca = l;
} else {
// hier ist der gefunden lca unter dem akutellen lca
pref[in[l]+1]++;
pref[in[u]+1]--;
}
}
}
vi summe(2 * n + 1);
partial_sum(pref.begin(), pref.end(), summe.begin());
vpii edges;
dfs2(adj, 0, 0, in, out, summe, edges, k);
sort(edges.begin(), edges.end());
int v,u;
cout << edges.size() << "\n";
for (pii e : edges) {
tie(v, u) = e;
cout << mapping[{v,u}] << " ";
// cout << ++v << " " << ++u << "\n";
}
}
