#include <iostream>
#include <cmath>
#include <map>
#include <unordered_map>
#include <set>
#include <queue>
#include <vector>
#include <string>
#include <algorithm>
#include <iomanip>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
typedef long long ll;
ll linf = 1e15+1;
using namespace std;
inline void scoobydoobydoo(){
ios::sync_with_stdio(false);
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
}
const int MAXN = 1e5+1;
set<pair<int, int> > s[MAXN];
int wutS[MAXN];
vector<int> children[MAXN];
int n, m, k;
int q = 0;
vector<pair<int, int>> adj[MAXN];
int nodeId[MAXN], binPar[MAXN][20];
vector<pair<int, int> > elemsNode[MAXN];
vector<pair<int, int>> ans;
pair<int, int> eulerTour[MAXN];
int counter = 0;
int depthNode[MAXN];
void rootTree(int node, int parent, int depth){
depthNode[node] = depth;
eulerTour[node].first = counter++;
//cout << node << " " << parent << " " << depth << " " << binPar[node][0] << endl;
for (auto& e : adj[node]){
if (e.first != parent){
children[node].push_back(e.first);
nodeId[e.first] = e.second;
binPar[e.first][0] = node;
rootTree(e.first, node, depth+1);
}
}
eulerTour[node].second = counter++;
}
void smallerToLarger(int node, int depth){
if (children[node].size() == 0){
wutS[node] = q;
for (auto& e : elemsNode[node]){
s[q].insert(e);
}
//cout << node << " " << s[q].size() << endl;
ans.push_back({s[q].size(), node});
q++;
return;
}
int maxiChild = -1, maxi = -1;
for (auto& e : children[node]){
smallerToLarger(e, depth+1);
//cout << e << ": " << node << ": " << wutS[e] << " " << (*s[wutS[e]].begin()).first << " " << (*s[wutS[e]].begin()).first << " " << s[wutS[e]].size() << endl;
int sZ = s[wutS[e]].size();
if (sZ > maxi){
//cout << "should be here" << endl;
maxiChild = e;
maxi = s[wutS[e]].size();
}
}
//cout << node << " _ " << maxiChild << endl;
wutS[node] = wutS[maxiChild];
for (auto& e : children[node]){
if (e != maxiChild){
for (auto& l : s[wutS[e]]){
s[wutS[node]].insert(l);
}
}
}
for (auto& e : elemsNode[node]){
s[wutS[node]].insert(e);
}
/*cout << "Ye1 " << node << " " << wutS[node] << endl;
for (auto& e : s[wutS[node]]){
cout << e.first << "," << e.second << " ";
}
cout << endl << endl;*/
while (true){
auto it = s[wutS[node]].lower_bound({depth, -1});
if (it == s[wutS[node]].end())break;
s[wutS[node]].erase(it);
}
/*cout << "Ye2 " << node << " " << wutS[node] << endl;
for (auto& e : s[wutS[node]]){
cout << e.first << "," << e.second << " ";
}
cout << endl << endl;*/
ans.push_back({s[wutS[node]].size(), node});
return;
}
void initBinPar(){
binPar[0][0] = 0;
for (int j = 1; j < 20; j++){
for (int i = 0; i < n; i++){
binPar[i][j] = binPar[binPar[i][j-1]][j-1];
}
}
return;
}
int jump(int node, int x){
for (int i = 20; i >= 0; i--){
if (x & (1<<i))node = binPar[node][i];
}
return node;
}
int lca(vector<int> v){
int minIn = 1e9, maxOut = -100;
for (int x : v){
minIn = min(minIn, eulerTour[x].first);
maxOut = max(maxOut, eulerTour[x].second);
}
for (int x : v){
if (eulerTour[x].first == minIn && eulerTour[x].second == maxOut)return depthNode[x];
}
int node = v[0];
for (int i = 18; i >= 0; i--){
int anc = binPar[node][i];
if (eulerTour[anc].first > minIn || eulerTour[anc].second < maxOut)node = anc;
}
node = binPar[node][0];
return depthNode[node];
}
int main(){
scoobydoobydoo();
//freopen("railway.in", "r", stdin);
cin >> n >> m >> k;
for (int i = 0; i < n-1; i++){
int a, b; cin >> a >> b;
a--; b--;
adj[a].push_back({b, i+1});
adj[b].push_back({a, i+1});
}
rootTree(0, 0, 0);
initBinPar();
/*for (int i = 0; i < n; i++){
cout << "N" << i << ": " << nodeId[i] << " ";
}
cout << endl; */
for (int i = 0; i < m; i++){
int l; cin >> l;
vector<int> v;
for (int j = 0; j < l; j++){
int t; cin >> t;
v.push_back(--t);
}
int d = lca(v);
//cout << d << endl;
for (int x : v){
elemsNode[x].push_back({d, i});
}
}
/*for (int i = 0; i < n; i++){
cout << i << ": ";
for (auto& e : elemsNode[i]){
cout << e.first << ", " << e.second << " ";
}
cout << endl;
}*/
smallerToLarger(0, 0);
/*for (int i = 0; i <= q; i++){
cout << i << ": ";
for (auto& e : s[i]){
cout << e.first << ", " << e.second << " ";
}
cout << endl;
}*/
sort(rall(ans));
vector<int> nAns;
for (int i = 0; i < ans.size() && ans[i].first >= k; i++){
//cout << ans[i].first << " " << ans[i].second << "; ";
nAns.push_back(nodeId[ans[i].second]);
}
//cout << endl;
sort(all(nAns));
cout << nAns.size() << endl;
for (auto& e : nAns){
cout << e << " ";
}
cout << endl;
return 0;
}
