// #include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <map>
#include <unordered_map>
#include <vector>
#include <iomanip>
#include <string>
#include <queue>
#include <set>
#include <deque>
using namespace std;
#define endl "\n"
#define pb push_back
#define int long long
#define fi first
#define se second
const int N = 3e5 + 5, M = 1e9 + 7, LG = 20;
int n , A[N] , m , k , In[N] , in = 1 , W[N] , sp[N][LG] , u , v , Dep[N] , sz , x;
map<pair<int,int> , int> mp;
vector<int> ans , lis[N];
void dfs(int v , int par){
Dep[v] = Dep[par]+1;
sp[v][0] = par;
In[v] = in;
in++;
for (int u : lis[v]){
if (par == u) continue;
dfs(u , v);
}
}
int lca(int u , int v){
if (Dep[v] > Dep[u]){
swap(u,v);
}
int dif = Dep[u] - Dep[v];
for (int i=LG-1 ; i>=0 ; i--){
if ((1<<i) & dif){
u = sp[u][i];
}
}
if (u == v){
return u;
}
for (int i=LG-1 ; i>=0 ; i--){
if (sp[u][i] != sp[v][i]){
u = sp[u][i];
v = sp[v][i];
}
}
return sp[u][0];
}
void dfs1(int v , int par){
for (int u : lis[v]){
if (u==par) continue;
dfs1(u , v);
W[v] += W[u];
}
if (W[v] >= k){
ans.pb(mp[{v,par}]);
}
}
void solve(){
cin >> n >> m >> k;
for (int i=1 ; i<n ; i++){
cin >> u >> v;
mp[{u,v}] = mp[{v,u}] = i;
lis[u].pb(v);
lis[v].pb(u);
}
dfs(1 , 1);
for (int i=1 ; i<LG ; i++){
for (int j=1 ; j<=n ; j++){
sp[j][i] = sp[sp[j][i-1]][i-1];
}
}
while(m--){
cin >> sz;
vector<pair<int,int>> p;
for (int i=1 ; i<=sz ; i++){
cin >> x;
W[x]++;
p.pb({In[x],x});
}
sort(p.begin(),p.end());
for (int i=0 ; i<sz ; i++){
W[lca(p[i].se , p[(i+1)%sz].se)]--;
}
}
dfs1(1 , 1);
cout << ans.size() << endl;
sort(ans.begin(),ans.end());
for (int i : ans){
cout << i << ' ';
}
cout << endl;
}
signed main(){
// freopen("" , "r" , stdin);
// freopen("" , "w" , stdout);
// cout << setprecision(30);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int ts = 1;
// cin >> ts;
while(ts--){
solve();
}
}
