#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
using namespace std;
const int mx=1e5+5;
typedef long long ll;
int mod=1e9+7;
const int MXm=22;
#define F first
#define S second
const int inf=1e9+10;
int aa[mx];
vector<int>adj[mx];
vector<pair<int,int>>edges;
int depth[mx];
int dp[20][mx];
int dp2[mx];
vector<int>a[mx] ;
void dfs(int node,int par){
dp[0][node]=par;
for(int j=1;j<19;j++){
dp[j][node]=dp[j-1][dp[j-1][node]];
}
for(auto it:adj[node]){
if(it==par){continue;}
depth[it]=depth[node]+1;
dfs(it,node);
}
return;
}
int kth(int node,int x){
for(int i=0;i<19;i++){
if(x&(1<<i)){
x-=(1<<i);
node=dp[i][node];
}
}
return node;
}
int lca(int a,int b){
if(depth[b]<depth[a]){swap(a,b);}
int dis=depth[b]-depth[a];
b=kth(b,dis);
// cout<<b;
if(a==b){return a;}
for(int j=19;j>=0;j--){
int aa=dp[j][a];int bb=dp[j][b];
if(aa==bb){continue;}
a=aa;b=bb;
}
return dp[0][a];
}
int n,m,k;
map<pair<int,int>,int>mp;
int dfs2(int node,int par){
int sum2=0;
for(auto it:adj[node]){
if(it==par){continue;}
int z= dfs2(it,node);
if(z>0){
int x=min(node,it);int y=max(node,it);
mp[{x,y}]++;
}
sum2+=z;
}
dp2[node]+=sum2;
//cout<<node<<" "<<dp2[node]<<endl;
return dp2[node];
}
void test(){
for(int i=1;i<=n;i++){
for(int j=i+1;j<=n;j++){
if(mp[{i,j}]){
cout<<i<<" "<<j<<endl;
}
}
}
}
void test2(){
vector<int>ans;
int anss=0;
for(int i=0;i<n;i++){
if(mp[{edges[i].first,edges[i].second}]>=k){
anss++;
ans.push_back(i+1);
}
}
cout<<anss<<endl;
for(auto it:ans){
cout<<it<<" ";
}
}
void solve(){
for(int i=0;i<m;i++){
int me=lca(a[i][0],a[i][1]);
dp2[me]-=2;
dp2[a[i][0]]++; dp2[a[i][1]]++;
}
dfs2(1,0);
}
void solve2(){
for(int i=0;i<m;i++){
memset(dp2,0,sizeof(dp2));
for(int j=0;j<a[i].size();j++){
for(int jj=j+1;jj<a[i].size();jj++){
int me=lca(a[i][j],a[i][jj]);
dp2[me]-=2;
dp2[a[i][j]]++; dp2[a[i][jj]]++;
// cout<<me<<endl;
}
}
dfs2(1,0);
}
}
int main(){
ios_base::sync_with_stdio(0) ;
cin.tie(0) ;
cin>>n>>m>>k;
for(int i=0;i<n-1;i++){
int a,b;cin>>a>>b;
if(b<a){swap(a,b);}
edges.push_back({a,b});
adj[a].push_back(b);
adj[b].push_back(a);
}
int leaf1=0;int leaf2=0;
dfs(1,0);
int ok=0; int ok2=1;
for(int i=0;i<m;i++){
int s;cin>>s;
for(int j=0;j<s;j++){
int x;cin>>x;
a[i].push_back(x);
}
if(k==m&&s==2){
}else{
ok=0;
}
// test();
//mp.clear();
// cout<<"test \n";
}
if(ok){
solve();
}else{
solve2();
}
test2();
/*
cout<<dp[1][6];
lca(6,5);
*/
}
