#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],subsz[N],tin2[N],timer2,ver[N],comp[N],deep[N],ttt,hakatin2[N];
bool all[4*N];
vector<pir> g[N];
vector<int> ans,poxel;
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];
deep[v]=deep[par]+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;
}
int dfssz(int v,int par=0){
subsz[v]=1;
trav(tv,g[v]){
int to=tv.fr;
if (to==par)continue;
subsz[v]+=dfssz(to,v);
}
return subsz[v];
}
int cnt=1;
pir sg[4*N];
void update(int v,int tl,int tr,int ind,pir val){
poxel.ad(v);
if (tl==tr){
sg[v]=val;
return;
}
int tm=(tl+tr)/2;
if (ind<=tm)update(v+v,tl,tm,ind,val);
else update(v+v+1,tm+1,tr,ind,val);
if (sg[v+v+1].fr==1)sg[v]=sg[v+v+1];
else sg[v]=sg[v+v];
//if (sg[v].sc==1){cout<<"stex el ka "<<tl<<" "<<tr<<" "<<ind<<endl;}
//if (tl==0 && tr==2)cout<<"stex piti urish lini "<<sg[v].fr<<" "<<sg[v].sc<<endl;
}
pir query(int v,int tl,int tr,int l,int r){
poxel.ad(v);
if (l>r)return {0,0};
//cout<<tl<<" "<<tr<<" "<<l<<" "<<r<<endl;
if (all[v]==ttt){
//cout<<"heeey "<<hakatin2[r]<<endl;
return {1,hakatin2[r]};
}
if (tl==l && tr==r){
//if (sg[v].sc==1) cout<<"arraaaa stexa "<<v<<" "<<tl<<" "<<tr<<endl;
all[v]=ttt;
pir nax=sg[v];
sg[v]={1,hakatin2[tr]};
return nax;
}
int tm=(tl+tr)/2;
pir q1=query(v+v+1,tm+1,tr,max(tm+1,l),r);
if (sg[v+v+1].fr==1)sg[v]=sg[v+v+1];
else sg[v]=sg[v+v];
if (q1.fr==1){
return q1;
}
q1 = query(v+v,tl,tm,l,min(r,tm));
if (sg[v+v+1].fr==1)sg[v]=sg[v+v+1];
else sg[v]=sg[v+v];
return q1;
}
int get(int a){
//cout<<"heeeeeeey "<<a<<" "<<tin2[1]<<" "<<tin2[a]<<endl;
while(true){
int ca=comp[a];
//cout<<ca<<endl;
//cout<<ca<<" "<<ver[ca]<<" "<<tin2[ver[ca]]<<endl;;
pir cur=query(1,0,n-1,tin2[ver[ca]],tin2[a]);
if (cur.fr==1){
return cur.sc;
}
a=anc[ver[ca]][0];
}
//cout<<"byeeeeee "<<endl;
return 0;
}
void decomp(int v,int par,int ham){
comp[v]=ham;
tin2[v]=timer2++;
//cout<<"haka "<<timer2-1<<" "<<v<<endl;
hakatin2[timer2-1]=v;
pir mx={INT_MIN,INT_MIN};
FOR(i,g[v].size()){
int to=g[v][i].fr;
if (to==par)continue;
mx=max(mx,{subsz[to],i});
}
if (mx.fr==INT_MIN)return;
swap(g[v][0],g[v][mx.sc]);
trav(tv,g[v]){
int to=tv.fr;
if (to==par)continue;
if (to==g[v][0].fr){
decomp(to,v,ham);
}
else{
ver[cnt]=to;
decomp(to,v,cnt++);
}
}
}
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});
}
dfssz(0);
ver[0]=0;
deep[0]=-1;
decomp(0,0,0);
while((1<<lg)<=n)lg++;
dfs(0);
for(ttt=1;ttt<=m;ttt++){
int s;
cin>>s;
vector<pir> vec;
FOR(i,s){
int a;
cin>>a;
a--;
vec.ad({deep[a],a});
}
sort(all(vec));
int lc=vec[0].sc;
FORT(i,1,s-1){
lc=lca(lc,vec[i].sc);
}
update(1,0,n-1,tin2[lc],{1,lc});
FOR(i,s){
qan[vec[i].sc]++;
int verevin=get(vec[i].sc);
qan[verevin]--;
//cout<<vec[i].sc<<" "<<verevin<<endl;
//update(1,0,n-1,tin2[vec[i].sc],{1,vec[i].sc});
}
trav(tv,poxel){
sg[tv]={0,0};
}
poxel.clear();
}
assert(dfs2(0)==0);
cout<<ans.size()<<endl;
sort(all(ans));
FOR(i,ans.size()){
cout<<ans[i]<<" ";
}
return 0;
}
/*
10 3 2
1 2
1 5
1 8
2 3
2 4
5 6
5 7
8 9
8 10
6 2 4 8 1 10 9
3 2 4 3
3 9 5 10
9 4 3
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
3 4 2 6
4 1 5 2 3
3 5 7 9
2 6 8
*/
