#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <functional>
using namespace std;
typedef long long int ll;
typedef vector<ll> vll;
typedef pair<ll, ll> pll;
typedef vector<vll> vvll;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef set<ll> sll;
typedef map<ll, sll> msll;
const ll MAXLOGN = 18;
const ll po2[MAXLOGN] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072};
#define rep(i, a, b) for (ll i = a; i < b; i++)
#define mp(a, b) make_pair(a, b)
#define sz(a) a.size()
#define pb(a) push_back(a)
ll n, m, k;
vvpll g;
vvll up;
vll edge;
vll depth;
vvpll charge;
void root_tree(ll cur, ll par) {
up[cur][0] = par;
for (vpll::iterator e = g[cur].begin(); e != g[cur].end(); e++) {
if (e->first == par) {
edge[cur] = e->second;
depth[cur] = depth[par] + 1;
} else {
root_tree(e->first, cur);
}
}
}
ll lca(ll a, ll b) {
// clamp to same depth
if (depth[a] > depth[b]) swap(a, b);
for (ll d = MAXLOGN - 1; d >= 0; d--) {
if (depth[b] - po2[d] >= depth[a]) b = up[b][d];
}
if (a == b) return a;
for (ll d = MAXLOGN - 1; d >= 0; d--) {
if (up[a][d] != up[b][d]) {
a = up[a][d];
b = up[b][d];
}
}
return up[a][0];
}
void union_merge_sll(sll& a, sll& b) {
if (sz(b) > sz(a)) swap(a, b);
for (sll::iterator itr = b.begin(); itr != b.end(); itr++) {
a.insert(*itr);
}
}
void union_merge_msll(msll& a, msll& b) {
if (sz(b) > sz(a)) swap(a, b);
for (msll::iterator itr = b.begin(); itr != b.end(); itr++) {
union_merge_sll(a[itr->first], b[itr->first]);
}
}
vll answer;
void pull_charge(ll cur, ll par, sll& ministers, msll& time) {
for (vpll::iterator e = g[cur].begin(); e != g[cur].end(); e++) {
if (e->first == par) continue;
sll new_ministers;
msll new_time;
pull_charge(e->first, cur, new_ministers, new_time);
union_merge_sll(ministers, new_ministers);
union_merge_msll(time, new_time);
}
// add charge at node
for (vpll::iterator itr = charge[cur].begin(); itr != charge[cur].end(); itr++) {
ministers.insert(itr->first);
time[itr->second].insert(itr->first);
}
// remove all with expired time == depth[cur]
for (sll::iterator itr = time[depth[cur]].begin(); itr != time[depth[cur]].end(); itr++) {
ministers.erase(*itr);
}
time.erase(depth[cur]);
// decide whether we include edge in planning
if (cur != 0) {
if (sz(ministers) >= k) {
answer.pb(edge[cur]);
}
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> k;
g.resize(n);
rep(i, 1, n) {
ll a, b;
cin >> a >> b;
a--; b--;
g[a].pb(mp(b, i));
g[b].pb(mp(a, i));
}
up.resize(n);
rep(i, 0, n) up[i].resize(MAXLOGN);
edge.resize(n);
edge[0] = -1;
depth.resize(n);
rep(i, 0, n) depth[i] = 0;
root_tree(0, -1);
// prep lca
rep(i, 1, MAXLOGN) {
rep(j, 0, n) {
if (up[j][i - 1] == -1) {
up[j][i] = -1;
} else {
up[j][i] = up[up[j][i - 1]][i - 1];
}
}
}
charge.resize(n);
// process queries
rep(q, 0, m) {
ll s;
cin >> s;
vll a(s);
rep(i, 0, s) {
cin >> a[i]; a[i]--;
}
ll lca_a = a[0];
rep(i, 1, s) {
lca_a = lca(lca_a, a[i]);
}
rep(i, 0, s) {
charge[a[i]].pb(mp(q, depth[lca_a]));
}
}
// calculate result
sll ministers;
msll time;
pull_charge(0, -1, ministers, time);
// answer
sort(answer.begin(), answer.end());
cout << sz(answer) << "\n";
rep(i, 0, sz(answer)) {
cout << answer[i] << " ";
}
cout << endl;
return 0;
}
