#include <bits/stdc++.h>
#define INF 1000000000
#define loop(var, start, cond, step) for (int var = start; var cond; var += step)
#define range(var, start, endExclusive) loop(var, start, < endExclusive, 1)
#define repeat(times) range(____i, 0, times)
#define foreach(idx, element, arr) for (int i = 0, element = arr[0]; i < (int) arr.size(); element = arr[++i])
#define dbg(expr) cout << #expr << " = " << expr << endl;
using namespace std;
using vi = vector<int>;
using ii = pair<int, int>;
using vvi = vector<vi>;
using vii = vector<ii>;
using ll = long long;
template <typename T>
istream& operator>>(istream& is, vector<T>& v) {
range(i, 0, v.size()) cin >> v[i];
return is;
}
template <typename T>
bool in_range(T lo, T hi, T t) {
return !(t < lo) && t < hi;
}
int n;
vi s, modified;
vvi tree, anc;
vi d, f, pref;
vii edges;
map<ii, int> cnt;
int t = 1;
void update(int j, int delta, int a = 1, int b = n * 2, int i = 1) {
if (a == b) {
s[i] += delta;
modified.push_back(i);
}
else {
int m = (a + b) / 2;
if (j <= m) update(j, delta, a, m, i * 2);
else update(j, delta, m + 1, b, i * 2 + 1);
s[i] = s[i * 2] + s[i * 2 + 1];
//cout << a << ".." << b << " = " << s[i] << endl;
modified.push_back(i);
}
}
int query(int l, int r, int a = 1, int b = n * 2, int i = 1) {
if (r < a || b < l) return 0;
if (l <= a && b <= r) return s[i];
int m = (a + b) / 2;
int left = query(l, r, a, m, i * 2);
int right = query(l, r, m + 1, b, i * 2 + 1);
//cout << "l=" << l << ", r=" << r << ", a=" << a << ", b = "<< b << ", sum = " << left + right << endl;
return left + right;
}
void pre(int u, int p) {
//d[u] = t++; cout << "discovery of " << u + 1 << " is " << d[u] << endl;
anc[u][0] = p;
for (int i = 1; i < 21; ++i) anc[u][i] = anc[anc[u][i - 1]][i-1];
for (int v : tree[u]) if (v != p) pre(v, u);
f[u] = t++;
//cout << "finish of " << u + 1 << " is " << f[u] << endl;
}
bool is_anc(int p, int a) {
return d[p] <= d[a] && f[a] <= f[p];
}
int lca(int a, int b) {
if (is_anc(a, b)) return a;
if (is_anc(b, a)) return b;
for (int step = 19; step >= 0; --step) {
if (!is_anc(anc[a][step], b)) a = anc[a][step];
}
return anc[a][0];
}
int dfs(int u, int p) {
int res = pref[u];
for (int v : tree[u]) if (v != p) {
int n = dfs(v, u);
res += n;
cnt[{ min(u, v), max(u, v) }] = n;
//cout << "edge " << u + 1 << ", " << v + 1 << " needed " << n << " times\n";
}
return res;
}
int main() {
#ifdef DEBUG
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
int m, k; cin >> n >> m >> k;
tree.resize(n), anc.resize(n, vi(21)), d.resize(n),
f.resize(n), pref.resize(n), edges.reserve(n - 1);
s.resize(n * 8, 0);
repeat(n - 1) {
int a, b; cin >> a >> b; a--; b--;
tree[a].push_back(b), tree[b].push_back(a);
edges.emplace_back(min(a, b), max(a, b));
}
pre(0, 0);
//for (int i = 0; i < n; ++i) cout << "parent of " << i + 1 << " is " << anc[i][0] + 1<< endl;
repeat(m) {
for (int i : modified) s[i] = 0;
modified.clear();
int c; cin >> c;
vi nodes(c);
for (int &n : nodes) {
cin >> n; --n;
pref[n]++;
//cout << "update " << d[n] << "(" << n + 1 << ") by +1\n";
update(d[n], +1);
}
sort(nodes.begin(), nodes.end(), [](int a, int b) { return is_anc(b, a); });
int ca = nodes[0];
for (int step = 19; step >= 0; --step) {
if (query(d[anc[ca][step]], f[anc[ca][step]]) < c) ca = anc[ca][step];
}
ca = anc[ca][0];
//cout << "common parent is " << ca + 1 << endl;
for (int n : nodes) {
//cout << "computing first LCA from " << n + 1 << endl;
for (int step = 19; step >= 0; --step) {
int a = anc[n][step];
int l = d[a], r = f[a];
int children = query(l, r);
if (children < 2) n = a;
}
n = anc[n][0];
//cout << "is " << n + 1 << endl;
int other_children = query(d[n], f[n]) - 1;
//cout << other_children << " other children (" << d[n] << ".." << f[n] << ")\n";
if (other_children == 0) continue;
//cout << "update " << d[n] << " by -" << other_children << endl;
update(d[n], -other_children);
pref[n] -= other_children;
}
//cout << "update " << d[ca] << " by -1\n";
update(d[ca], -1);
pref[ca]--;
}
//for (int i = 0; i < n; ++i) cout << "v " << i + 1 << " = " << pref[i] << endl;
dfs(0, 0);
vi ans;
for (int i = 0; i < edges.size(); ++i) {
if (cnt[edges[i]] >= k) ans.push_back(i);
}
cout << ans.size() << endl;
for (int e : ans) cout << e + 1 << " ";
return 0;
}
