// Om Namah Shivaya
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a, b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a, b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
refs:
https://cp-algorithms.com/graph/hld.html (hld tutorial)
*/
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
vector<pll> adj[N];
struct lca_algo {
// LCA template (for graphs with 1-based indexing)
int LOG = 1;
vector<int> depth;
vector<vector<int>> up;
lca_algo() {
}
lca_algo(int n) {
lca_init(n);
}
void lca_init(int n) {
while ((1 << LOG) < n) LOG++;
up = vector<vector<int>>(n + 1, vector<int>(LOG, 1));
depth = vector<int>(n + 1);
lca_dfs(1, -1);
}
void lca_dfs(int node, int par) {
for(auto [child, id] : adj[node]) {
if (child == par) conts;
up[child][0] = node;
rep1(j, LOG - 1) {
up[child][j] = up[up[child][j - 1]][j - 1];
}
depth[child] = depth[node] + 1;
lca_dfs(child, node);
}
}
int lift(int u, int k) {
rep(j, LOG) {
if (k & (1 << j)) {
u = up[u][j];
}
}
return u;
}
int query(int u, int v) {
if (depth[u] < depth[v]) swap(u, v);
int k = depth[u] - depth[v];
u = lift(u, k);
if (u == v) return u;
rev(j, LOG - 1, 0) {
if (up[u][j] != up[v][j]) {
u = up[u][j];
v = up[v][j];
}
}
u = up[u][0];
return u;
}
int get_dis(int u, int v) {
int lca = query(u, v);
return depth[u] + depth[v] - 2 * depth[lca];
}
};
template<typename T>
struct fenwick {
int siz;
vector<T> tree;
fenwick(int n) {
siz = n;
tree = vector<T>(n + 1);
}
int lsb(int x) {
return x & -x;
}
void build(vector<T> &a, int n) {
for (int i = 1; i <= n; ++i) {
int par = i + lsb(i);
tree[i] += a[i];
if (par <= siz) {
tree[par] += tree[i];
}
}
}
void pupd(int i, T v) {
while (i <= siz) {
tree[i] += v;
i += lsb(i);
}
}
T sum(int i) {
T res = 0;
while (i) {
res += tree[i];
i -= lsb(i);
}
return res;
}
T query(int l, int r) {
if (l > r) return 0;
T res = sum(r) - sum(l - 1);
return res;
}
};
vector<ll> tin(N), tout(N);
vector<ll> depth(N), subsiz(N);
vector<pll> par(N);
ll timer = 1;
void dfs(ll u, ll p){
tin[u] = timer++;
subsiz[u] = 1;
for(auto [v, id] : adj[u]) {
if(v == p) conts;
par[v] = {u, id};
depth[v] = depth[u] + 1;
dfs(v,u);
subsiz[u] += subsiz[v];
}
tout[u] = timer++;
}
vector<ll> head(N), pos(N);
ll curr_pos = 1;
void decompose(ll u, ll p, ll h){
head[u] = h;
pos[u] = curr_pos++;
ll mx = -1, heavy = -1;
for(auto [v, id] : adj[u]){
if(v == p) conts;
if(subsiz[v] > mx){
mx = subsiz[v];
heavy = v;
}
}
if(heavy != -1){
decompose(heavy, u, h);
}
for(auto [v, id] : adj[u]){
if(v == p or v == heavy) conts;
decompose(v, u, v);
}
}
fenwick<ll> fenw(N);
void upd(ll u, ll v, ll add){
for (; head[u] != head[v]; v = par[head[v]].ff) {
if (depth[head[u]] > depth[head[v]])
swap(u,v);
fenw.pupd(pos[head[v]], add);
fenw.pupd(pos[v]+1, -add);
}
if(depth[u] > depth[v]){
swap(u,v);
}
fenw.pupd(pos[u], add);
fenw.pupd(pos[v]+1, -add);
}
void solve(int test_case)
{
ll n,m,need; cin >> n >> m >> need;
rep1(i,n-1){
ll u,v; cin >> u >> v;
adj[u].pb({v, i}), adj[v].pb({u, i});
}
dfs(1,-1);
decompose(1,-1,1);
lca_algo LCA(n);
// auto upd = [&](ll u, ll v){
// while(u != v){
// auto [p, id] = par[u];
// cnt[id]++;
// u = p;
// }
// };
while(m--){
ll k; cin >> k;
vector<pll> a(k);
rep(j,k){
ll u; cin >> u;
a[j] = {tin[u], u};
}
sort(all(a));
vector<pll> b;
rep(i,k){
b.pb({depth[a[i].ss], a[i].ss});
if(i+1 < k){
ll lca = LCA.query(a[i].ss, a[i+1].ss);
b.pb({depth[lca], lca});
}
}
sort(rall(b));
b.resize(unique(all(b)) - b.begin());
set<pll> st;
for(auto [d, u] : b){
ll l = tin[u], r = tout[u];
auto it = st.lower_bound({l,-1});
vector<pll> torem;
for(; it != st.end() and it->first <= r; ++it){
torem.pb(*it);
upd(it->second, u, 1);
upd(u,u,-1);
}
trav(p,torem){
st.erase(p);
}
st.insert({tin[u], u});
}
assert(sz(st) == 1);
}
vector<ll> ans;
rep1(u,n){
if(u == 1) conts;
ll id = par[u].ss;
ll cnt = fenw.query(1, pos[u]);
if(cnt >= need){
ans.pb(id);
}
}
sort(all(ans));
cout << sz(ans) << endl;
trav(x,ans) cout << x << " ";
cout << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
