//source: https://oj.uz/problem/view/BOI17_railway
#include <bits/stdc++.h>
using namespace std;
const int mxN = 100000, K = 17;
int n, m, k, id[mxN];
int tin[mxN], tout[mxN], timer = 0;
int anc[mxN][K];
vector<pair<int, int>> adj[mxN];
void dfs(int u = 0, int p = -1) {
tin[u] = timer++;
anc[u][0] = p;
for (int i = 1; i < K; ++i) {
anc[u][i] = anc[u][i - 1] == -1 ? -1 : anc[anc[u][i - 1]][i - 1];
}
for (pair<int, int> v : adj[u]) {
if (v.first != p) {
id[v.first] = v.second;
dfs(v.first, u);
}
}
tout[u] = timer++;
}
bool is_anc(int a, int b) {
return tin[a] <= tin[b] && tout[a] >= tout[b];
}
int lca(int a, int b) {
//assert(tin[a] <= tin[b]);
if (is_anc(a, b)) {
return a;
}
//cout << a << " " << b << " ";
for (int i = K - 1; ~i; --i) {
if (anc[a][i] != -1 && !is_anc(anc[a][i], b)) {
a = anc[a][i];
}
}
//cout << a << " " << anc[a][0] << "\n";
return anc[a][0];
}
/*int bit[2 * mxN + 1];
void upd(int i, int val) {
for (++i; i <= 2 * n; i += i & -i) {
bit[i] += val;
}
}
int qry(int a, int b) {
int res = 0;
for (++a; a > 0; a -= a & -a) {
res += bit[a];
}
for (++b; b > 0; b -= b & -b) {
res -= bit[b];
}
return res;
}*/
int cnt[2 * mxN];
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; ++i) {
int a, b;
cin >> a >> b, --a, --b;
adj[a].emplace_back(b, i);
adj[b].emplace_back(a, i);
}
dfs();
/*for (int i = 0; i < n; ++i) {
cout << tin[i] << " " << tout[i] << "\n";
}*/
for (int i = 0; i < m; ++i) {
int num;
cin >> num;
vector<int> pos(num);
for (int& i : pos) {
cin >> i, --i;
}
sort(pos.begin(), pos.end(), [](int a, int b) {return tin[a] < tin[b];});
pos.push_back(pos[0]);
//cout << "POS: ";
for (int i = 0; i < num; ++i) {
//cout << pos[i] << " ";
//upd(tin[pos[i]], 1);
//upd(tin[pos[(i + 1) % num]], 1);
--cnt[tin[pos[i]] + 1];
--cnt[tin[pos[i + 1]] + 1];
int l = lca(pos[i], pos[i + 1]);
//cout << "LCA: " << pos[i] << " " << pos[i + 1] << " " << l << "\n";
cnt[tin[l] + 1] += 2;
}
//cout << "\n";
}
for (int i = 1; i < 2 * n; ++i) {
cnt[i] += cnt[i - 1];
}
vector<int> ans;
for (int i = 1; i < n; ++i) {
//int num = qry(tin[i], tout[i]);
int num = cnt[tin[i]] - cnt[tout[i]];
//cout << num << "\n";
if (num >= 2 * k) {
ans.push_back(id[i]);
}
}
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (int i : ans) {
cout << i << " ";
}
return 0;
}
