#include <bits/stdc++.h>
using namespace std;
#define sz(v) (int)v.size()
#define fi first
#define sc second
const int MAXN = 1e5+5;
vector<int> adj[MAXN], id[MAXN];
int pai[MAXN], pid[MAXN], freq[MAXN];
map<int,int> mp[MAXN];
void marca(int a, int b, int c){
int cur = a;
while(cur != c){
freq[pid[cur]]++;
cur = pai[cur];
}
cur = b;
while(cur != c){
freq[pid[cur]]++;
cur = pai[cur];
}
}
void merge(int p , int f){
if(sz(mp[p]) > sz(mp[f])){
for(auto it : mp[f]){
if(mp[p].find(it.fi) == mp[p].end()) mp[p][it.fi] = it.sc;
else{
marca(it.sc, mp[p][it.fi], p);
mp[p][it.fi] = p;
}
}
}
else{
for(auto it : mp[p]){
if(mp[f].find(it.fi) == mp[f].end()) mp[f][it.fi] = it.sc;
else{
marca(it.sc, mp[f][it.fi], p);
mp[f][it.fi] = p;
}
}
swap(mp[f],mp[p]);
}
mp[f].clear();
}
void dfs(int s){
for(int i = 0; i < sz(adj[s]); i++){
int viz = adj[s][i];
if(viz != pai[s]){
pai[viz] = s;
pid[viz] = id[s][i];
dfs(viz);
merge(s,viz);
}
}
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n,m,k; cin>>n>>m>>k;
for(int i = 1; i < n; i++){
int a,b; cin>>a>>b;
adj[a].push_back(b); id[a].push_back(i);
adj[b].push_back(a); id[b].push_back(i);
}
for(int i = 1; i <= m; i++){
int s; cin>>s;
for(int j = 1; j <= s; j++){
int v; cin>>v;
mp[v][i] = v;
}
}
dfs(1);
int ans = 0;
for(int i = 1; i < n; i++)
if(freq[i] >= k)ans++;
cout<<ans<<"\n";
for(int i = 1; i < n; i++)
if(freq[i] >= k)cout<<i<<" ";
cout<<"\n";
}
