#include<bits/stdc++.h>
#define f first
#define s second
using namespace std;
long long n,m,k,aa,bb,cnt,ind[100005],t,timer,in[100005],out[100005],par[100005][50],psum[100005],vis[100005],vis2[100005];
vector<pair<long long,long long> > ve;
vector<long long> adj[100005];
map<pair<long long,long long>,long long> mp;
vector<long long> ans;
void dfs(long long x,long long pre){
vis[x]=1;
in[x]=timer; timer++;
par[x][0]=pre;
for (int i=1;i<=40;i++) par[x][i]=par[par[x][i-1]][i-1];
cnt++;
ind[x]=cnt;
for (int ii=0;ii<adj[x].size();ii++){
if (!vis[adj[x][ii]]) dfs(adj[x][ii],x);
}
out[x]=timer; timer++;
return;
}
bool an(long long u,long long v){
return in[u]<=in[v] && out[u]>=out[v];
}
long long lca(long long u,long long v){
if (an(u,v)) return u;
if (an(v,u)) return v;
for (int i=39;i>=0;--i){
if (!an(par[u][i],v)) u=par[u][i];
}
return par[u][0];
}
void dfs2(long long x,long long pre){
vis2[x]=1;
for (int i=0;i<adj[x].size();i++){
if (vis2[adj[x][i]]) continue;
dfs2(adj[x][i],x);
psum[x]+=psum[adj[x][i]];
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin>>n>>m>>k;
for (int i=1;i<n;i++){
cin>>aa>>bb;
mp[{aa,bb}]=i;
mp[{bb,aa}]=i;
adj[aa].push_back(bb);
adj[bb].push_back(aa);
}
dfs(1,1);
while (m--){
cin>>t;
ve.clear();
for (int i=0;i<t;i++){
long long tmp;
cin>>tmp;
ve.push_back({ind[tmp],tmp});
}
sort(ve.begin(),ve.end());
for (int i=0;i<t;i++){
long long u=ve[i].s;
long long v=ve[(i+1)%ve.size()].s;
long long lc=lca(u,v);
psum[u]++; psum[v]++; psum[lc]-=2;
}
}
dfs2(1,1);
for (int i=1;i<=n;i++) {
//cout<<psum[i]<<endl;
if (psum[i]>=2*k){
ans.push_back(mp[{i,par[i][0]}]);
}
}
sort(ans.begin(),ans.end());
cout<<ans.size()<<endl;
for (int i=0;i<ans.size();i++){
if (i==0) cout<<ans[i];
else cout<<" "<<ans[i];
}
cout<<endl;
}
