#include <bits/stdc++.h>;
#define int long long
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
const int li = 2e5 + 10;
void print() { cerr << '\n'; }
template<typename T, typename... Args>
void print(T first, Args... rest) {
cerr << first << ' ';
print(rest...);
}
int n, m, k;
pii e[li];
vi qu[li], adj[li];
int cnt = 0, topo[li], max_child[li];
void build_dfs_tree(int node = 1) {
topo[node] = ++cnt;
max_child[node] = topo[node];
for (int v : adj[node]) {
if (!topo[v]) {
build_dfs_tree(v);
max_child[node] = max(max_child[node], max_child[v]);
}
}
}
int ecnt[li];
void solve1() {
build_dfs_tree();
int ans = 0;
for (int i=1; i<=n-1; i++) {
int u = e[i].first, v = e[i].second;
int x = (topo[u] > topo[v] ? u : v);
for (int j=1; j<=m; j++) {
bool inside = 0, outside = 0;
for (int nei : qu[j]) {
if (topo[nei] >= topo[x] && topo[nei] <= max_child[x]) inside = 1;
else outside = 1;
if (inside && outside) { ecnt[i]++; break; }
}
}
if (ecnt[i] >= k) ans++;
}
cout << ans << '\n';
for (int i=1; i<=n-1; i++) if (ecnt[i] >= k) cout << i << ' ';
}
int dfscnt[li], choose[li];
vi g[li];
bool vis[li];
void _dfs(int s, int node = 1) {
// print(" ", node);
vis[node] = 1;
if (choose[node] > 0) dfscnt[node] += choose[node];
for (int ee : g[node]) {
pii other = e[ee];
int v = other.first + other.second - node;
if (!vis[v]) {
_dfs(s, v);
if (dfscnt[v] > 0 && dfscnt[v] < s) ecnt[ee]++;
dfscnt[node] += dfscnt[v];
}
}
// print(" ",node, dfscnt[node]);
}
void solve2() {
for (int i=1; i<=m; i++) {
// print(i);
memset(vis, 0, sizeof(vis));
memset(choose, 0, sizeof(choose));
memset(dfscnt, 0, sizeof(dfscnt));
for (int cur : qu[i]) choose[cur]++;
_dfs(qu[i].size());
}
int ans = 0;
for (int i=1; i<=n-1; i++) if (ecnt[i] >= k) ans++;
cout << ans << '\n';
for (int i=1; i<=n-1; i++) if (ecnt[i] >= k) cout << i << ' ';
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m >> k;
for (int i=1, x, y; i<=n-1; i++) {
cin >> x >> y;
e[i] = {x, y};
adj[x].push_back(y);
adj[y].push_back(x);
g[x].push_back(i);
g[y].push_back(i);
}
for (int i=1; i<=m; i++) {
int s, x; cin >> s;
for (int j=1; j<=s; j++) { cin >> x; qu[i].push_back(x); }
}
solve2();
return 0;
}
