/* Dirty code by Articulation_points */
#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e5;
const int MAXLG=16;
int n,m,k,x,y,timer,tin[MAXN+5],tout[MAXN+5],h[MAXN+5],anc[MAXN+5][MAXLG+5];
pair<int,int>dp[MAXN+5];
vector<pair<int,int>>adj[MAXN+5];
void dfs1(int u, int p){
tin[u]=++timer;
for(pair<int,int>tmp:adj[u]){
int v=tmp.first;
int idx=tmp.second;
if(v==p)
continue;
h[v]=h[u]+1;
anc[v][0]=u;
dp[v].second=idx;
dfs1(v,u);
}
tout[u]=timer;
}
void build(){
for(int j=1;j<=MAXLG;++j)
for(int i=1;i<=n;++i)
if(h[i]-(1<<j)>=0)
anc[i][j]=anc[anc[i][j-1]][j-1];
}
bool is_anc(int u, int v){
return (tin[u]<=tin[v]&&tout[u]>=tout[v]);
}
int lca(int u, int v){
if(h[u]>h[v])
swap(u,v);
if(is_anc(u,v))
return u;
for(int i=MAXLG;i>=0;--i)
if(h[u]-(1<<i)>=0&&!is_anc(anc[u][i],v))
u=anc[u][i];
return anc[u][0];
}
void dfs2(int u, int p){
for(pair<int,int>tmp:adj[u]){
int v=tmp.first;
if(v==p)
continue;
dfs2(v,u);
dp[u].first+=dp[v].first;
}
}
signed main(){
cin.tie(0)->sync_with_stdio(false);
cout.tie(0);
cin>>n>>m>>k;
for(int i=1;i<n;++i){
cin>>x>>y;
adj[x].push_back({y,i});
adj[y].push_back({x,i});
}
dfs1(1,0);
build();
for(int i=1;i<=m;++i){
vector<pair<int,int>>v;
cin>>x;
for(int j=1;j<=x;++j){
cin>>y;
v.push_back({tin[y],y});
}
sort(v.begin(),v.end());
v.push_back({tin[v[0].second],v[0].second});
for(int j=1;j<v.size();++j){
dp[v[j].second].first++;
dp[v[j-1].second].first++;
dp[lca(v[j].second,v[j-1].second)].first-=2;
}
}
dfs2(1,0);
vector<int>ans;
for(int i=2;i<=n;++i)
if(dp[i].first/2>=k)
ans.push_back(dp[i].second);
cout<<ans.size()<<'\n';
sort(ans.begin(),ans.end());
for(int x:ans)
cout<<x<<' ';
}
