#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define endl "\n"
const int MOD = 998244353;
vector<int> ans;
pair<set<int>, map<int, int>> DFS(int x, vector<vector<pair<int, int>>>& adj, vector<vector<int>>& mn, vector<int>& cnt, int p, int id, int k){
set<int> pos;
map<int, int> m;
for(int y : mn[x]){
if(cnt[y] != 1){
m[y]++;
pos.insert(y);
}
}
for(auto pr : adj[x]){
int node = pr.first;
if(node == p) continue;
auto t = DFS(node, adj, mn, cnt, x, pr.second, k);
if(x != 0){
if((int)pos.size() < (int)t.first.size()) swap(pos, t.first);
for(auto x : t.first){
pos.insert(x);
}
if((int)m.size() < (int)t.second.size()) swap(m, t.second);
for(auto pr : t.second){
m[pr.first] += pr.second;
int y = m[pr.first];
if(y == cnt[pr.first]) {pos.erase(pr.first); m.erase(pr.first);}
}
}
}
if(x != 0){
if((int)pos.size() >= k) ans.push_back(id);
}
return {pos, m};
}
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<vector<int>> mn(n);
vector<int> cnt(m);
for(int i = 0; i < m; i++){
int s; cin >> s;
set<int> st;
while(s--){
int x; cin >> x; x--;
bool good = st.count(x);
if(!good){
st.insert(x);
mn[x].push_back(i);
}
}
cnt[i] = (int)st.size();
}
DFS(0, adj, mn, cnt, -1, -1, k);
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();
}
}
