#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ld long double
#define ff first
#define ss second
#define ln "\n"
#define mp make_pair
#define pb push_back
#define INF (ll)2e18
#define MOD (ll)(1e9+7)
ll n, m, k;
struct edge{
ll u, v, i;
};
vector<vector<ll>> A, bin;
vector<edge> e;
vector<ll> level, tin, pref;
void dfs1(ll u, ll p, ll clev, ll &timer){
tin[u]=timer; timer++;
level[u]=clev; bin[u][0]=p;
for (ll i=1; i<20; i++) bin[u][i]=bin[bin[u][i-1]][i-1];
for (auto i:A[u]){
ll v = e[i].u^e[i].v^u;
if (v!=p){
dfs1(v, u, clev+1, timer);
}
}
}
ll lca(ll u, ll v){
if (level[u]<level[v]) swap(u, v);
ll jmp = level[u]-level[v];
for (ll i=0; i<20; i++){
if ((1<<i)&(jmp)) u=bin[u][i];
}
if (u==v) return u;
for (ll i=19; i>=0; i--){
if (bin[u][i]!=bin[v][i]) {
u=bin[u][i]; v=bin[v][i];
}
}
return bin[u][0];
}
void dfs3(ll u, ll p, vector<ll> &res){
for (auto i:A[u]){
ll v = e[i].u^e[i].v^u;
if (v==p) continue;
dfs3(v, u, res);
// cout << u << " <-> " << v << ": " << pref[v] << ln;
if (pref[v]>=k) res.push_back(e[i].i);
pref[u]+=pref[v];
}
}
void solve(){
cin >> n >> m >> k;
A.resize(n+1); e.resize(n); tin.resize(n+1);
bin.resize(n+1, vector<ll>(21)); pref.resize(n+1);
level.resize(n+1);
for (ll i=1; i<=n-1; i++){
ll u, v; cin >> u >> v; e[i] = {u, v, i};
A[u].push_back(i); A[v].push_back(i);
}
ll timer=0; dfs1(1, 1, 0, timer);
while (m--){
ll a; cin >> a; vector<ll> vs(a);
for (ll i=0; i<a; i++){
cin >> vs[i];
}
sort(vs.begin(), vs.end(), [&](ll op1, ll op2){ return tin[op1]<tin[op2]; });
// for (auto ch:vs) cout << tin[ch] << " ";
// cout << ln;
pref[vs[0]]++; pref[lca(vs[0], vs.back())]--;
for (ll i=1; i<(ll)vs.size(); i++){
pref[vs[i]]++; pref[lca(vs[i-1], vs[i])]--;
}
}
vector<ll> res;
dfs3(1, 1, res);
sort(res.begin(), res.end());
cout << res.size() << ln;
for (auto ch:res) cout << ch << " ";
cout << ln;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr);
#ifdef LOCAL
auto start = chrono::high_resolution_clock::now();
#endif
ll t=1;
// cin >> t;
while (t--) solve();
#ifdef LOCAL
auto duration = chrono::duration_cast<chrono::microseconds>(chrono::high_resolution_clock::now() - start);
cout << setprecision(0) << fixed << "time: " << (double)duration.count()/1000.0 << " milliseconds" << endl;
#endif
}
