///In the name of GOD
//#pragma GCC optimize("O2")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MXN = 1e5 + 10;
const ll LOG = 17;
ll n, q, m, k, timer;
ll Stm[MXN], val[MXN];
ll Jad[LOG][MXN], dis[MXN];
vector<pair<ll, ll>> Edge;
vector<ll> adj[MXN], S, ANS;
void prep(ll u, ll par){
Jad[0][u] = par, Stm[u] = ++ timer;
for(int i = 1; i < LOG; i ++) Jad[i][u] = Jad[i - 1][Jad[i - 1][u]];
for(auto v : adj[u]){
if(v != par) dis[v] = dis[u] + 1, prep(v, u);
}
}
ll K_Jad(ll u, ll k){
for(int i = 0; i < LOG; i ++){
if((k >> i) & 1LL) u = Jad[i][u];
}
return u;
}
ll LCA(ll u, ll v){
if(dis[u] > dis[v]) swap(u, v);
v = K_Jad(v, dis[v] - dis[u]);
if(u == v) return u;
for(int i = LOG - 1; ~i; i --){
if(Jad[i][u] != Jad[i][v]){
u = Jad[i][u], v = Jad[i][v];
}
}
return Jad[0][u];
}
void Add(ll u, ll v){
ll lca = LCA(u, v);
val[u] ++, val[v] ++, val[lca] -= 2;
//cout << "Q : " << u << ' ' << v << " -> " << lca << '\n';
}
void Arch(){
sort(S.begin(), S.end(), [&](const int &u, const int &v){
return Stm[u] < Stm[v];
});
for(int i = 0; i < m - 1; i ++) Add(S[i], S[i + 1]);
Add(S[0], S[m - 1]);
}
void flood(ll u, ll par){
for(auto v : adj[u]){
if(v != par){
flood(v, u);
val[u] += val[v];
}
}
}
int main(){
ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
cin >> n >> q >> k; k *= 2;
for(int i = 1; i < n; i ++){
ll u, v; cin >> u >> v;
adj[u].push_back(v), adj[v].push_back(u);
Edge.push_back({u, v});
}
prep(1, 0);
//for(int i = 1; i <= n; i ++) cout << Stm[i] << ' '; cout << '\n';
for(int i = 1; i <= q; i ++){
S.clear(); cin >> m;
for(int j = 0; j < m; j ++){
ll u; cin >> u;
S.push_back(u);
}
Arch();
}
flood(1, 0);
int id = 0;
for(auto e : Edge){
ll u, v; tie(u, v) = e; id ++;
if(dis[u] > dis[v]) swap(u, v);
if(val[v] >= k) ANS.push_back(id);
}
cout << ANS.size() << '\n';
for(auto X : ANS) cout << X << ' ';
cout << '\n';
return 0;
}
/*!
HE'S AN INSTIGATOR,
ENEMY ELIMINATOR,
AND WHEN HE KNOCKS YOU BETTER
YOU BETTER LET HIM IN.
*/
//! N.N
