#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define f first
#define s second
#define pb push_back
#define pf push_front
#define pi pair<int,int>
#define vi vector<int>
const int MAX = 1e6+10;
int d[MAX];
//vi up[MAX];
vi g[MAX];
set<int> val[MAX];
map<pi,int>mp;
const int lmax= 30;
int up[MAX][40];
int timer;
int tin[MAX], tout[MAX];
set<int>st;
vector<int>add[MAX];
vector<int>del[MAX];
vi cnt;
void dfs(int from, int p, int dep){
d[from]= dep;
up[from][0]=p;
tin[from] =++timer;
// cout << " T " <<timer<<endl;
for(int i =1 ; i <= lmax; i++){
up[from][i]= up[up[from][i-1]][i-1];
}
for(int to : g[from]){
if(to==p) continue;
// cout << "f " << from<<endl;
dfs(to,from,dep+1);
}
tout[from]=++timer;
}
bool is_ancestor(int a, int b){
return tin[a]<=tin[b] && tout[a]>= tout[b];
}
int lca(int u, int v){
//cout <<"U "<< u << " " << tin[u]<< " " << tout[u]<<endl;
//cout << "V "<< v << " " << tin[v]<< " " << tout[v]<<endl;
if(is_ancestor(u,v)) return u;
else if(is_ancestor(v,u)) return v;
//cout <<u << " " << v<< " SDA"<<endl;
for(int i = lmax; i >= 0; i--){
// cout << u << endl;
if(!is_ancestor(up[u][i], v)) u = up[u][i];
}
return up[u][0];
}
set<int> dfs2(int from, int p){
set<int>h;
set<int>r;
for(int to : g[from]){
if(to==p) continue;
r = dfs2(to,from);
/* cout << to << " " << from<<endl;
for(int i : r){
cout << i << " ";
}
// cout <<endl<<"R: "<< r.size()<< " "<<mp[{from,to}]<<" "<< mp[{to,from}]<<endl;
//cout << endl<<endl;
*/
int a = from, b= to;
cnt[mp[{from,to}]] =r.size();
cnt[mp[{to,from}]] = r.size();
if(h.size() > r.size()){
swap(h,r);
}
for(int i : r){
h.insert(i);
}
}
for(int i : add[from]){
h.insert(i);
}
for(int i : del[from]){
h.erase(i);
}
return h;
}
int main(){
int n,m,k;
cin >> n>>m>>k;
pi coor[n];
cnt.resize(n);
ll a,b;
for(int i = 1; i < n; i++){
cin >> a >>b;
if(a>b)swap(a,b);
mp[{a,b}]= i;
mp[{b,a}]=i;
g[a].pb(b);
g[b].pb(a);
coor[i]={a,b};
}
dfs(1,1,0);
int q;
int ind = 1;
for(int i =0 ; i < m; i++){
cin >> q;
vector<pi> ord;
for(int i = 0; i < q; i++){
cin >> a;
ord.pb({d[a],a});
}
sort(ord.begin(),ord.end());
for(int j = 0; j < q; j++){
for(int k = j+1; k < q; k++){
int h = ord[j].s;
int p = ord[k].s;
// cout << h << " " << p<< " " << lca(h,p)<<endl;
//cout << "IND: " <<ind<<endl;
add[h].pb(ind);
add[p].pb(ind);
del[lca(h,p)].pb(ind);
}
}
ind++;
}
dfs2(1,-1);
vi ans;
for(int i =1; i < n;i++){
if(cnt[mp[coor[i]]]>=k){
// cout << coor[i].f << " "<< coor[i].s << " " << mp[coor[i]]<<endl;
ans.pb(i);
}
}
sort(ans.begin(),ans.end());
cout << ans.size() << endl;
for(int i : ans){
cout << i << " ";
}
cout << endl;
}
