#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl "\n"
const int MOD = 998244353;
struct segTree {
int size;
vector<pair<ll, int>> minimum;
void init(int n){
size = 1;
while (size < n) size *= 2;
minimum.assign(2 * size, {1e18, 1});
}
void build(vector<int> &a, int x, int lx, int rx){
if (rx - lx == 1){
if (lx < (int)a.size()){
minimum[x] = {a[lx], lx};
}
return;
}
int m = (lx + rx) / 2;
build(a, 2 * x + 1, lx, m);
build(a, 2 * x + 2, m, rx);
minimum[x] = min(minimum[2 * x + 1], minimum[2 * x + 2]);
}
void build(vector<int>& a){
build(a, 0, 0, size);
}
pair<ll, int> calc(int l, int r, int x, int lx, int rx){
if (lx >= r || l >= rx)
return {1e18, 1};
if (lx >= l && rx <= r){
return minimum[x];
}
int m = (lx + rx) / 2;
pair<ll, int> s1 = calc(l, r, 2 * x + 1, lx, m);
pair<ll, int> s2 = calc(l, r, 2 * x + 2, m, rx);
return min(s1, s2);
}
ll calc(int l, int r){
return calc(l, r, 0, 0, size).second;
}
};
struct segTree2{
int size;
vector<ll> sums;
void init(int n){
size = 1;
while (size < n) size *= 2;
sums.assign(2 * size, 0LL);
}
void set(int i, int v, int x, int lx, int rx){
if (rx - lx == 1){
sums[x] += v;
return;
}
int m = (lx + rx) / 2;
if (i < m){
set(i, v, 2 * x + 1, lx, m);
}else{
set(i, v, 2 * x + 2, m, rx);
}
sums[x] = sums[2 * x + 1] + sums[2 * x + 2];
}
void set(int i, int v){
set (i, v, 0, 0, size);
}
ll sum(int l, int r, int x, int lx, int rx){
if (lx >= r || l >= rx){
return 0;
}
if (lx >= l && rx <= r){
return sums[x];
}
int m = (lx + rx) / 2;
ll s1 = sum(l, r, 2 * x + 1, lx, m);
ll s2 = sum(l, r, 2 * x + 2, m, rx);
return s1 + s2;
}
ll sum (int l, int r){
return sum(l, r, 0, 0, size);
}
};
int cnt = 0;
void build_euler(int x, vector<vector<pair<int, int>>>& adj, vector<int>& depths, vector<int>& euler_depth, vector<int>& euler, vector<pair<int, int>>& t, vector<pair<int, int>>& t2, vector<int>& pos, vector<int>& id, int p, int edge){
t[x].first = (int)euler.size();
t2[x].first = cnt; pos[cnt] = x; cnt++;
id[x] = edge;
euler.push_back(x); euler_depth.push_back(depths[x]);
for(auto pr : adj[x]){
int node = pr.first;
if(node == p) continue;
depths[node] = depths[x] + 1;
build_euler(node, adj, depths, euler_depth, euler, t, t2, pos, id, x, pr.second);
t[x].second = (int)euler.size();
euler.push_back(x); euler_depth.push_back(depths[x]);
}
if(t[x].first + 1 == (int)euler.size()){
t[x].second = (int)euler.size();
euler.push_back(x); euler_depth.push_back(depths[x]);
}
t2[x].second = cnt; pos[cnt] = x; cnt++;
}
void solve(){
int n, m, k; cin >> n >> m >> k;
vector<vector<pair<int, int>>> adj(n);
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});
}
vector<int> depths(n, 0);
vector<int> euler_depth;
vector<int> euler;
vector<int> id(n);
vector<pair<int, int>> t(n);
vector<pair<int, int>> t2(n);
vector<int> pos(2 * n);
build_euler(0, adj, depths, euler_depth, euler, t, t2, pos, id, -1, -1);
segTree lca;
lca.init((int)euler.size()); lca.build(euler_depth);
vector<int> lc(m);
vector<vector<int>> mn(n);
segTree2 lcas; lcas.init(2 * n);
for(int q = 0; q < m; q++){
int s; cin >> s;
vector<int> v(s); for(auto &i : v) cin >> i; for(int i = 0; i < s; i++) v[i]--;
int l = v[0];
mn[v[0]].push_back(q);
set<int> done; done.insert(v[0]);
for(int i = 1; i < s; i++){
bool good = done.count(v[i]);
if(good) continue;
done.insert(v[i]);
mn[v[i]].push_back(q);
l = euler[lca.calc(min(t[l].first, t[v[i]].first), max(t[l].second, t[v[i]].second))];
}
lc[q] = l;
lcas.set(t2[l].first, 1);
}
//I have to do one Euler for the different ministers in the subtree.
//Another one for the LCAs in my subtree, and substract.
segTree2 ministers; ministers.init(2 * n);
vector<int> lst(m, -1);
vector<vector<int>> next(2 * n);
for(int i = 0; i < 2 * n; i++){
for(int x : mn[pos[i]]){
if(lst[x] == -1) {lst[x] = i; ministers.set(i, 1);}
else {next[lst[x]].push_back(i); lst[x] = i;}
}
}
vector<pair<int, int>> queries(n);
for(int i = 0; i < n; i++) queries[i] = {t2[i].first, t2[i].second};
sort(queries.begin(), queries.end());
vector<int> ans;
int l = 0;
for(auto p : queries){
while(l < p.first){
for(int y : next[l]) ministers.set(y, 1);
l++;
}
int mini = ministers.sum(p.first, p.second + 1) - lcas.sum(p.first, p.second + 1);
//cout << "P.first "<< p.first << " "<< p.second << " pos "<< pos[p.first] << " "<< mini << endl;
//cout << "Sum "<< ministers.sum(p.first, p.second + 1) << " lca "<< lcas.sum(p.first, p.second + 1) << endl;
if(mini >= k){
ans.push_back(id[pos[p.first]]);
}
}
sort(ans.begin(), ans.end()); cout << ans.size() << endl; for(int x : ans) {cout << x << " ";} cout << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("inpt.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
//int tt; cin >> tt;
int tt = 1;
for(int t = 1; t <= tt; t++){
//cout << "Case #"<<t << ": ";
solve();
}
}
