#include <bits/stdc++.h>
#define fst first
#define snd second
#define pb push_back
#define SZ(x) (int)x.size()
#define forn(i,a,b) for(int i = a; i < b; i++)
#define FIN ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
typedef long long ll;
const int MAXN = 100000+5;
ll n,m,k;
ll lvl[MAXN];
ll prnt[MAXN];
vector<ll> cAdj[MAXN];
vector<ll> adj[MAXN];
set<ll> ndSet[MAXN];
ll obj[MAXN]; //Objetivo de conexiones del ministro I
ll aCon[MAXN]; //Conexiones actuales del objetivo i
map<pair<ll,ll>,ll> mp;
void dfs(ll nd,ll p,ll lv){
lvl[nd]=lv;
prnt[nd]=p;
for(auto i:adj[nd]) if(i!=p) dfs(i,nd,lv+1);
}
void solve(){
priority_queue<pair<ll,ll>> pq;
forn(i,0,n) pq.push({lvl[i],i});
while(!pq.empty()){
ll nd = pq.top().snd; pq.pop();
forn(i,0,SZ(adj[nd])){
if(adj[nd][i]==prnt[nd]) continue;
cAdj[nd][i]+=SZ(ndSet[adj[nd][i]]);
if(SZ(ndSet[nd])<SZ(ndSet[adj[nd][i]])) swap(ndSet[nd],ndSet[adj[nd][i]]);
for(auto j:ndSet[adj[nd][i]]){
auto h = ndSet[nd].find(j);
if(h!=ndSet[nd].end()){
aCon[*h]++;
if(aCon[*h]==obj[*h]){ ndSet[nd].erase(h); continue; }
}
ndSet[nd].insert(j);
}
}
}
vector<pair<ll,ll>> res;
forn(i,0,n){
forn(j,0,SZ(cAdj[i])){
if(cAdj[i][j]>=k) res.pb({min((ll)i,adj[i][j]),max((ll)i,adj[i][j])});
}
}
cout<<SZ(res)<<'\n';
for(auto i:res){
cout<<mp[i]<<" ";
}
cout<<'\n';
}
int main(){
cin>>n>>m>>k;
ll u,v;
forn(i,0,n-1){
cin>>u>>v; u--; v--;
mp[{min(u,v),max(u,v)}]=i+1;
adj[u].pb(v);
cAdj[u].pb(0);
adj[v].pb(u);
cAdj[v].pb(0);
}
dfs(0,-1,0);
ll t;
ll aux;
forn(i,0,m){
cin>>t;
obj[i]=t-1;
aCon[i]=0;
forn(j,0,t){
cin>>aux; aux--;
ndSet[aux].insert(i);
}
}
solve();
return 0;
}
