#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pi;
typedef vector<int> vi;
typedef vector<pi> vpi;
#define f first
#define s second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define mp make_pair
const int mx = 100005;
int n, m, k;
int a[mx];
int b[mx];
vpi adj[mx];
vpi s[mx];
int etind[mx];
int edgeind[mx];
int curetind = 0;
void genET(int node, int prv = -1){
etind[node] = ++curetind;
for(auto u: adj[node]){
if(u.f == prv) continue;
genET(u.f, node);
edgeind[u.f] = u.s;
}
}
vi queries[mx];
int sum[mx];
vi ances;
vi e;
int get(int a){
if(e[a] < 0) return a;
e[a] = get(e[a]);
return e[a];
}
bool unite(int a, int b){
a = get(a);
b = get(b);
if(a == b) return 0;
if(-e[a] < -e[b]) swap(a, b);
e[a]+=e[b];
e[b] = a;
if(etind[ances[a]] > etind[ances[b]]){
ances[a] = ances[b];
}
return 1;
}
void genLCA(int node, int prv = -1){
for(auto u: queries[node]){
sum[ances[get(u)]]-=2;
}
for(auto u: adj[node]){
if(u.f == prv) continue;
genLCA(u.f, node);
unite(u.f, node);
}
}
void genSums(int node, int prv = -1){
for(auto u: adj[node]){
if(u.f == prv) continue;
genSums(u.f, node);
sum[node]+=sum[u.f];
}
}
int main(){
int n, m, k;
cin >> n >> m >> k;
ances = e = vi(n+5, -1);
for(int i = 1; i <= n; i++){
ances[i] = i;
}
for(int i = 1; i <= n-1; i++){
cin >> a[i] >> b[i];
adj[a[i]].pb(mp(b[i], i));
adj[b[i]].pb(mp(a[i], i));
}
genET(1);
for(int i = 1; i <= m; i++){
int num;
cin >> num;
for(int j = 0; j < num; j++){
int x;
cin >> x;
s[i].pb(mp(etind[x], x));
}
sort(all(s[i]));
s[i].pb(s[i][0]);
}
for(int i = 1; i <= m; i++){
for(int j = 0; j < sz(s[i])-1; j++){
int a = s[i][j].s;
int b = s[i][j+1].s;
if(etind[a] > etind[b]) swap(a, b);
queries[b].pb(a);
sum[a]++;
sum[b]++;
}
}
genLCA(1);
genSums(1);
vi ans;
for(int i = 2; i <= n; i++){
if(sum[i]/2 >= k){
ans.pb(edgeind[i]);
}
}
sort(all(ans));
cout << sz(ans) << "\n";
for(auto u: ans){
cout << u << " ";
}
cout << "\n";
}
