#include <bits/stdc++.h>
using namespace std;
vector<vector<pair<int,int>>> adjlist;
vector<int> depth;
vector<set<int>> sets;
vector<int> loc;
vector<vector<int>> nadd;
vector<vector<int>> nremove;
vector<int> ans;
int pk[100000][20];
int n,k;
void dfs(int node, int parent){
for (auto p : adjlist[node]){
if (p.first==parent){continue;}
int i=p.first;
pk[i][0]=node;
depth[i]=depth[node]+1;
dfs(i,node);
}
}
void decom2k(){
for (int i = 1; i<20; i++){
for (int j = 0; j<n; j++){
if (pk[j][i-1]!=-1){
pk[j][i]=pk[pk[j][i-1]][i-1];
}
}
}
}
int lca(int a, int b){
//wlog a deeper
if (depth[b]>depth[a]){
swap(a,b);
}
for (int i = 19; i>=0; i--){
if (pk[a][i]==-1){continue;}
if (depth[pk[a][i]]>=depth[b]){
a=pk[a][i];
}
}
if (a==b){
return a;
}
for (int i = 19; i>=0; i--){
if (pk[a][i]==-1){continue;}
if (pk[a][i]!=pk[b][i]){
a=pk[a][i];b=pk[b][i];
}
}
return pk[a][0];
}
void setdfs(int node, int parent){
if (parent!=-1&&adjlist[node].size()==1&&adjlist[node][0].first==parent){
for (int i : nadd[node]){
sets[loc[node]].insert(i);
}
for (int i : nremove[node]){
sets[loc[node]].erase(i);
}
return;
}
int largestset = -1;
int largestnode = -1;
for (auto p : adjlist[node]){
if (p.first==parent){continue;}
setdfs(p.first,node);
int s = sets[loc[p.first]].size();
if (s>=k){
ans.push_back(p.second);
}
if (s>largestset){
largestnode=p.first;
largestset=s;
}
}
for (auto p : adjlist[node]){
if (p.first==parent){continue;}
if (p.first==largestset){continue;}
for (int i : sets[loc[p.first]]){
sets[loc[largestnode]].insert(i);
}
}
loc[node]=loc[largestnode];
for (int i : nadd[node]){
sets[loc[node]].insert(i);
}
for (int i : nremove[node]){
sets[loc[node]].erase(i);
}
}
int main(){
cin.tie(0);
ios_base::sync_with_stdio(0);
int m;
cin>>n>>m>>k;
adjlist.resize(n);
depth.resize(n,0);
nadd.resize(n);
nremove.resize(n);
sets.resize(n);
loc.resize(n);
for (int i = 0; i<n-1; i++){
loc[i]=i;
int a,b;
cin>>a>>b;
a--;b--;
adjlist[a].push_back({b,i});
adjlist[b].push_back({a,i});
}
loc[n-1]=n-1;
pk[0][0]=-1;
dfs(0,-1);
decom2k();
for (int i = 0; i<m; i++){
int num;
cin>>num;
int prevlca = -1;
for (int j = 0; j<num; j++){
int x;
cin>>x;
x--;
nadd[x].push_back(i);
if (prevlca==-1){
prevlca=x;
} else {
prevlca=lca(prevlca,x);
}
}
//cout<<prevlca<<endl;
nremove[prevlca].push_back(i);
}
setdfs(0,-1);
sort(ans.begin(),ans.end());
cout<<ans.size()<<'\n';
for (int i : ans){
cout<<i+1<<" ";
}cout<<'\n';
}
