// In the name of God
// Hope is last to die
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define pb push_back
// #define int long long
#define S second
#define F first
#define mp make_pair
#define smax(x, y) (x) = max((x), (y))
#define smin(x, y) (x) = min((x), (y))
#define all(x) (x).begin(), (x).end()
#define len(x) ((int)(x).size())
const int maxn = 1e5 + 5;
const int inf = 1e9 + 7;
int n, m, k, ans, cnt[maxn], a[maxn], sz[maxn];
vector<pii> adj[maxn];
vector<int> col[maxn], vec;
bool mark[maxn];
int get_sz(int v, int p){
for(auto [u, i]: adj[v]){
if(u != p) sz[v] += get_sz(u, v);
}
return ++sz[v];
}
void reset(){
for(auto v: vec){
for(auto c: col[v]){
a[c]--;
if(a[c] == cnt[c] - 1) ans++;
else if(a[c] == 0) ans--;
}
}
vec.clear();
}
void add(int v){
vec.pb(v);
for(auto c: col[v]){
a[c]++;
if(a[c] == 1) ans++;
else if(a[c] == cnt[c]) ans--;
}
}
void dfs2(int v, int p){
add(v);
for(auto [u, i]: adj[v]) if(u != p) dfs2(u, v);
}
void dfs(int v, int p, int e){
int bc = -1, bi = -1;
for(auto [u, i]: adj[v]){
if(u != p) if(bc == -1 || sz[u] > sz[bc]){
bc = u;
bi = i;
}
}
for(auto [u, i]: adj[v]){
if(u != p && u != bc){
dfs(u, v, i);
reset();
}
}
if(bc != -1) dfs(bc, v, bi);
for(auto [u, i]: adj[v]){
if(u != p && u != bc){
dfs2(u, v);
}
}
add(v);
if(ans >= k) mark[e] = 1;
}
int32_t main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for(int i = 0; i < n - 1; i++){
int u, v; cin >> u >> v;
adj[u].pb(mp(v, i));
adj[v].pb(mp(u, i));
}
for(int i = 0; i < m; i++){
cin >> cnt[i];
for(int j = 0; j < cnt[i]; j++){
int u; cin >> u;
col[u].pb(i);
}
}
get_sz(1, -1);
dfs(1, -1, -1);
vector<int> res;
for(int i = 0; i < n - 1; i++) if(mark[i]) res.pb(i);
cout << res.size() << '\n';
for(auto u: res) cout << u + 1 << ' ';
cout << '\n';
return 0;
}
