#include <bits/stdc++.h>
using namespace std;
#define print(l) for(auto i:l) cout<<i<<" ";cout<<endl;
#define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i];
#define int long long
#define pb push_back
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define all(l) l.begin(),l.end()
#define pii pair<int,int>
#define fi first
#define se second
const int N = 1e6+10;
const int lg = log2(N)+1;
const int M = 1e9+7;
const int inf = 1e18;
void io(){
#ifndef ONLINE_JUDGE
freopen("cowland.in","r",stdin);
freopen("cowland.out","w",stdout);
#endif
}
int bp(int x, int y, int p){
int res = 1;
x = x % p;
while (y > 0) {
if (y & 1)
res = (res * x) % p;
y = y >> 1;
x = (x * x) % p;
}
return res;
}
int MI(int n, int p){
return bp(n, p - 2, p);
}
int mul(int x,int y, int p){
return x * 1ull * y % p;
}
int di(int x,int y, int p){
return mul(x, MI(y, p), p);
}
int n , m , k , q;
int ti;
vector<vector<int>>adj;
vector<int>intime;
vector<int>dis,sum;
vector<int>ans;
int sp[N][lg];
void dfs(int v,int par){
intime[v] = ti;
ti++;
sp[v][0] = par;
for(int i:adj[v]){
if(i == par){
continue;
}
dis[i] = min(dis[i],dis[v]+1);
dfs(i,v);
}
}
int lca(int u,int v){
if(dis[u] > dis[v] ){
swap(u,v);
}
int d = dis[v]-dis[u];
for(int i = lg-1;i>=0;i--){
if(d&(1<<i)){
v = sp[v][i];
d-=(1<<i);
}
}
if(u == v){
return u;
}
for(int i = lg-1;i>=0;i--){
if(sp[u][i] != sp[v][i]){
u = sp[u][i];
v = sp[v][i];
}
}
// cout<<u<<" "<<v<<endl;
return sp[v][0];
}
map<pair<int, int>, int> E;
vector<int> op;
int an;
void dfs1(int v,int par){
sum[v] = ans[v];
for (auto i : adj[v]){
if (i == par) continue;
dfs1(i,v);
sum[v] += sum[i];
}
if (sum[v] >= k and v!= 1) {
an++;
// cout<<par<<" "<<v<<endl;
op.push_back(E[{par, v}]);
}
}
void solve(int testcase_number){
cin>>n>>m>>k;
an = 0;
ti = 0;
adj.resize(n+1);
ans.resize(n+1,0);
sum.resize(n+1,0);
intime.resize(n+1);
dis.resize(n+1,inf);
for(int i = 0;i<n-1;i++){
int u,v;
cin>>u>>v;
E[{u,v}] = i+1;
E[{v,u}] = i+1;
adj[u].pb(v);
adj[v].pb(u);
// cout<<u<<" "<<v<<endl;
}
// print(adj[1]);
dis[1] = 0;
sp[1][0] = 1;
intime[1] = 0;
dfs(1,1);
for(int i = 1;i<lg;i++){
for(int j = 1;j<=n;j++){
sp[j][i] = sp[sp[j][i-1]][i-1];
}
}
for(int i = 0;i<m;i++){
vector<pair<int,int>>ord;
int sz;
cin>>sz;
input(int,st,sz);
for(int j:st){
ans[j]++;
ord.pb({intime[j],j});
}
sort(all(ord));
for(int i = 0;i+1<sz;i++){
ans[lca(ord[i].se,ord[i+1].se)]--;
}
ans[lca(ord[0].se,ord.back().se)]--;
}
dfs1(1,1);
cout<<an<<endl;
sort(all(op));
for(auto i:op){
cout<<i<<" ";
}
cout<<endl;
}
signed main(){
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);
cout << fixed<<setprecision(9);
int t = 1;
// cin>>t;
for(int i = 1;i<=t;i++){
solve(i);
}
}
