#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define FOR(i,a) for (int i=0;i<(a);++i)
#define FORD(i,a) for (int i=(a)-1;i>=0;i--)
#define FORT(i,a,b) for (int i=(a);i<=(b);++i)
#define FORTD(i,b,a) for (int i=(b);i>=(a);--i)
#define trav(i,v) for (auto i : v)
#define all(v) v.begin(),v.end()
#define ad push_back
#define fr first
#define sc second
#define mpr(a,b) make_pair(a,b)
#define pir pair<int,int>
#define all(v) v.begin(),v.end()
#define make_unique(v) v.erase(unique(all(v)),v.end())
#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define srng mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define y1 EsiHancagorcRepa
const int N=1e5+10;
const ll MOD=1e9+7;
int n,m,k,lg,timer,tin[N],tout[N],anc[N][20],qan[N];;
vector<pir> g[N];
vector<int> ans;
void dfs(int v,int par=0){
tin[v]=timer++;
anc[v][0]=par;
FORT(i,1,lg) anc[v][i]=anc[anc[v][i-1]][i-1];
trav(tv,g[v]){
int to=tv.fr;
if (to==par){
continue;
}
dfs(to,v);
}
tout[v]=timer++;
}
bool upper(int a,int b){
return tin[a]<=tin[b] && tout[b]<=tout[a];
}
int lca(int a,int b){
if (upper(a,b))return a;
if (upper(b,a))return b;
FORD(i,lg+1){
if (!upper(anc[a][i],b)){
a=anc[a][i];
}
}
return anc[a][0];
}
int dfs2(int v,int par=0){
int tiv=qan[v];
//cout<<v<<" "<<tiv<<endl;
trav(tv,g[v]){
int to=tv.fr;
if (to==par)continue;
int cur=dfs2(to,v);
if (cur>=k){
ans.ad(tv.sc);
}
tiv+=cur;
}
return tiv;
}
set<int> st;
int get(int a){
//cout<<tin[a]<<endl;
if (st.lower_bound(tin[a])!=st.end() && *st.lower_bound(tin[a])==tin[a]) return a;
FORD(i,lg+1){
if (st.lower_bound(tin[anc[a][i]])==st.lower_bound(tout[anc[a][i]]+1)){
a=anc[a][i];
//cout<<"hey "<<a<<endl;
}
}
return anc[a][0];
}
int main(){
fastio;
srng;
cin>>n>>m>>k;
FOR(i,n-1){
int a,b;
cin>>a>>b;
a--;
b--;
g[a].ad({b,i+1});
g[b].ad({a,i+1});
}
while((1<<lg)<=n)lg++;
dfs(0);
FOR(ttt,m){
int s;
cin>>s;
vector<pir> vec;
FOR(i,s){
int a;
cin>>a;
a--;
vec.ad({tin[a],a});
}
sort(all(vec));
int lc=vec[0].sc;
FORT(i,1,s-1){
lc=lca(lc,vec[i].sc);
}
//cout<<lc<<endl;
st.insert(tin[lc]);
//cout<<"added "<<tin[lc]<<endl;
FOR(i,s){
qan[vec[i].sc]++;
int verevin=get(vec[i].sc);
//cout<<vec[i].sc<<" "<<verevin<<endl;
qan[verevin]--;
st.insert(tin[vec[i].sc]);
//cout<<"added "<<tin[vec[i].sc]<<endl;
}
st.clear();
}
assert(dfs2(0)==0);
cout<<ans.size()<<endl;
sort(all(ans));
FOR(i,ans.size()){
cout<<ans[i]<<" ";
}
return 0;
}
