#include<bits/stdc++.h>
#define fi first
#define se second
#define pitem item*
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<ll> vl;
const int N=1e5+10;
const int SS=1<<19;
const int INFi=2e9;
const ll INFl=1e13;
const ll mod2=998244353;
const ll mod=1e9+7;
const ll mod3=1000696969;
const ll p=70032301;
const ull p2=913;
const int L=17;
int n,m,k,oj[N],il[N],jump[N][L+1],pre[N],l,dep[N],dod[N];
pair<int,int> w[N];
vi graf[N];
void dfs(int v,int o){
jump[v][0]=o;
for(int i=1;i<=L;i++) jump[v][i]=jump[jump[v][i-1]][i-1];
pre[v]=++l;
dep[v]=dep[o]+1;
for(auto u:graf[v]){
if(u==o) continue;
dfs(u,v);
}
}
void dfs2(int v,int o){
il[v]+=dod[v];
for(auto u:graf[v]){
if(u==o) continue;
dfs2(u,v);
il[v]+=il[u];
}
}
int lca(int a,int b){
if(dep[a]<dep[b]) swap(a,b);
for(int i=L;i>=0;i--) if(dep[jump[a][i]]>=dep[b]) a=jump[a][i];
if(a==b) return a;
int res=0;
for(int i=L;i>=0;i--){
if(jump[a][i]==jump[b][i]) res=jump[a][i];
else a=jump[a][i],b=jump[b][i];
}
return res;
}
void solve(){
cin>>n>>m>>k;
k<<=1;
for(int a,b,i=1;i<n;i++){
cin>>a>>b;
graf[a].push_back(b),graf[b].push_back(a);
w[i]={a,b};
}
dfs(1,1);
for(int i=1;i<n;i++){
if(dep[w[i].fi]<dep[w[i].se]) oj[w[i].se]=i;
else oj[w[i].fi]=i;
}
for(int i=1;i<=m;i++){
int xd;
cin>>xd;
vector<pair<int,int> >v;
while(xd--){
int curr;
cin>>curr;
v.push_back({pre[curr],curr});
}
sort(v.begin(),v.end());
v.push_back(v[0]);
for(int j=0;j<v.size()-1;j++) dod[v[j].se]++,dod[v[j+1].se]++,dod[lca(v[j].se,v[j+1].se)]-=2;
}
dfs2(1,1);
vi res;
for(int i=2;i<=n;i++) if(il[i]>=k) res.push_back(oj[i]);
cout<<res.size()<<"\n";
sort(res.begin(),res.end());
for(auto u:res) cout<<u<<" ";
cout<<"\n";
}
int main(){
ios_base::sync_with_stdio(0),cin.tie(0);
solve();
}
