#include <bits/stdc++.h>
#define int long long
using namespace std;
int a,b,k;
vector <int> z[1000005];
int d[1000005];
int sta1[1000005];
int fin1[1000005];
int tour1;
int high[1000005];
vector <int> res;
int logarit[1000005];
int sta[1000005];
int fin[1000005];
int euler[1000005];
int tour;
pair<int,int> edge[1000005];
int val[1000005];
int st[300001][21];
vector <int> v;
void dfs(int i,int parent){
tour++;
sta[i]=tour;
euler[tour]=i;
tour1++;
sta1[i]=tour1;
for (auto p:z[i]){
if (p==parent){
continue;
}
high[p]=high[i]+1;
dfs(p,i);
tour++;
euler[tour]=i;
}
fin1[i]=tour1;
}
bool isanc(int x,int y){
return sta1[x]>=sta1[y] && fin1[x]<=fin1[y];
}
bool cmp(int a,int b){
return sta1[a]<sta1[b];
}
void buildst(){
for (int i=1;i<=tour;i++){
st[i][0]=euler[i];
}
for (int j=1;j<=20;j++){
for (int i=1;i+(1<<j)-1<=tour;i++){
int l=st[i][j-1];
int r=st[i+(1<<(j-1))][j-1];
if (high[l]<high[r]){
st[i][j]=l;
}else{
st[i][j]=r;
}
}
}
}
int lca(int x,int y){
int l=min(sta[x],sta[y]);
int r=max(sta[x],sta[y]);
int j=logarit[r-l+1];
int idx1=st[l][j];
int idx2=st[r-(1<<j)+1][j];
if (high[idx1]<high[idx2]){
return idx1;
}else{
return idx2;
}
}
void auxiliary(){
sort(v.begin(),v.end(),cmp);
int sz=v.size();
for (int i=0;i<sz-1;i++){
int pre= lca(v[i],v[i+1]);
v.push_back(pre);
}
sort(v.begin(),v.end(),cmp);
v.erase(unique(v.begin(),v.end()),v.end());
int auxroot=v[0];
stack<int> st;
st.push(auxroot);
for (int i=1;i<v.size();i++){
int u=v[i];
while (st.size() && !isanc(u,st.top())){
st.pop();
}
int g=st.top();
d[u]++;
d[g]--;
// cout << u << " " << g << "\n";
st.push(u);
}
}
void dfs1(int i,int par){
val[i]=d[i];
for (auto p:z[i]){
if (p==par){
continue;
}
dfs1(p,i);
val[i]+=val[p];
}
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> a >> b >> k;
logarit[1]=0;
for (int i=2;i<=1e6;i++){
logarit[i]=logarit[i/2]+1;
}
for (int i=1;i<a;i++){
int x,y;
cin >> x >> y;
z[x].push_back(y);
z[y].push_back(x);
edge[i]={x,y};
}
dfs(1,0);
buildst();
while (b--){
int c;
cin >> c;
for (int i=1;i<=c;i++){
int x;
cin >> x;
v.push_back(x);
}
auxiliary();
v.clear();
}
dfs1(1,0);
for (int i=1;i<a;i++){
auto [x,y]=edge[i];
if (high[x]<high[y]){
swap(x,y);
}
if (val[x]>=k){
// cout << val[x] << " " << x << "\n";
res.push_back(i);
}
}
cout << res.size() << "\n";
for (auto p:res){
cout << p << " ";
}
return 0;
}
