#include <bits/stdc++.h>
using namespace std;
using ii = pair<int, int>;
using vi = vector<int>;
using vvi = vector<vi>;
int n, m, k;
vvi tree, anc;
vi discovery, finish, v, ans;
map<ii, int> edge_idx;
int t = 0;
void pre(int u, int p) {
discovery[u] = t++;
anc[u][0] = p;
for (int i = 1; i < 20; ++i) anc[u][i] = anc[anc[u][i - 1]][i - 1];
for (int v : tree[u]) if (v != p) pre(v, u);
finish[u] = t++;
}
bool is_anc(int a, int b) {
return discovery[a] <= discovery[b] && finish[b] <= finish[a];
}
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 = v[u];
for (int v : tree[u]) if (v != p) {
int c = dfs(v, u);
res += c;
if (c >= k) ans.push_back(edge_idx[{ u, v }]);
}
return res;
}
int main() {
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n >> m >> k;
tree.resize(n); anc.resize(n, vi(20));
discovery.resize(n); finish.resize(n); v.resize(n);
for (int i = 1; i < n; ++i) {
int a, b; cin >> a >> b; a--; b--;
tree[a].push_back(b); tree[b].push_back(a);
edge_idx[{a, b}] = edge_idx[{b, a}] = i;
}
pre(0, 0);
for (int i = 0; i < m; ++i) {
int s; cin >> s;
vi nodes(s);
for (int &x : nodes) {
cin >> x; x--;
v[x]++;
}
sort(nodes.begin(), nodes.end(), [&](int a, int b) { return discovery[a] < discovery[b]; });
for (int j = 0; j < s; ++j) {
int a = nodes[j], b = nodes[(j + 1) % s];
int l = lca(a, b);
v[l]--;
}
}
dfs(0, -1);
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
for (int e : ans) cout << e << " ";
}
