#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int MAX_N = 1e5 + 5, INF = 1e9;
int n, m, k;
map<pii, int> edge_ind; // Both ways
array<vector<int>, MAX_N> adj;
array<vector<int>, MAX_N> children;
int n_inds;
array<int, MAX_N> ind, f_ind, rev_ind;
array<array<int, 20>, MAX_N> anc;
void dfs1(int u = 1) {
n_inds++, ind[u] = n_inds, rev_ind[n_inds] = u;
for (int v : adj[u])
if (!ind[v]) children[u].push_back(v), anc[v][0] = u, dfs1(v);
f_ind[u] = n_inds;
}
bool is_anc(int u, int v) { return ind[u] <= ind[v] && ind[v] <= f_ind[u]; }
int lca(int u, int v) {
if (is_anc(u, v)) return u;
if (is_anc(v, u)) return v;
for (int i = 19; i >= 0; i--)
if (anc[u][i] != 0 && !is_anc(anc[u][i], v))
u = anc[u][i];
u = anc[u][0];
return u;
}
void precomp() {
dfs1();
for (int i = 1; i < 20; i++)
for (int u = 1; u <= n; u++)
anc[u][i] = anc[anc[u][i - 1]][i - 1];
}
array<vector<int>, MAX_N> add, del;
array<unordered_set<int>, MAX_N> groups;
array<int, MAX_N> n_groups;
void merge(unordered_set<int>& x, unordered_set<int>& y) { // y ---> x
if (x.size() < y.size()) x.swap(y);
for (int z : y) x.insert(z);
}
void dfs2(int u = 1) {
for (int v : children[u])
dfs2(v), merge(groups[u], groups[v]);
groups[u].insert(add[u].begin(), add[u].end());
for (int x : del[u])
if (groups[u].count(x)) groups[u].erase(x);
// cout << u << ": ";
// for (int x : groups[u]) cout << x << " ";
// cout << endl;
n_groups[u] = groups[u].size();
}
int main() {
// freopen("rail.in", "r", stdin);
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v; cin >> u >> v;
edge_ind[{u, v}] = edge_ind[{v, u}] = i;
adj[u].push_back(v), adj[v].push_back(u);
}
precomp();
for (int i = 1; i <= m; i++) {
int siz; cin >> siz;
vector<int> nodes;
for (int j = 1; j <= siz; j++) {
int u; cin >> u;
nodes.push_back(u);
add[u].push_back(i);
}
int min_ind = INF, max_ind = -1;
for (int u : nodes) min_ind = min(min_ind, ind[u]), max_ind = max(max_ind, ind[u]);
int lca_node = lca(rev_ind[min_ind], rev_ind[max_ind]);
del[lca_node].push_back(i);
// cout << i << ": " << lca_node << endl;
}
dfs2();
set<int> ans;
for (int u = 2; u <= n; u++) {
if (n_groups[u] < k) continue;
int par = anc[u][0];
ans.insert(edge_ind[{u, par}]);
}
cout << ans.size() << '\n';
for (int u : ans) cout << u << " ";
cout << '\n';
}
