#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define dbg(...) 47
#endif
constexpr int N = 1e5;
constexpr int M = 20;
vector<pair<int, int>> g[N];
int lvl[N], to[N][M], t[N], tin[N], timer = 0;
void dfs_lvl(int u, int p) {
tin[u] = timer++;
to[u][0] = p;
for (int i = 1; i < M; i++) {
to[u][i] = to[to[u][i - 1]][i - 1];
}
for (auto [v, _] : g[u]) {
if (v == p) continue;
lvl[v] = lvl[u] + 1;
dfs_lvl(v, u);
}
}
int lca(int u, int v) {
if (lvl[u] < lvl[v]) swap(u, v);
int diff = lvl[u] - lvl[v];
for (int i = 0; i < M; i++) {
if (diff & (1 << i)) {
u = to[u][i];
}
}
if (u == v) return u;
for (int i = M - 1; i >= 0; i--) {
if (to[u][i] != to[v][i]) {
u = to[u][i];
v = to[v][i];
}
}
return to[u][0];
}
void update(int u, int v) {
t[u]++;
t[v]++;
t[lca(u, v)] -= 2;
}
void dfs(int u, int p) {
for (auto [v, _] : g[u]) {
if (v == p) continue;
dfs(v, u);
t[u] += t[v];
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u--; v--;
g[u].push_back({v, i});
g[v].push_back({u, i});
}
dfs_lvl(0, 0);
for (int i = 0; i < m; i++) {
int s;
cin >> s;
vector<int> a(s);
for (int j = 0; j < s; j++) {
cin >> a[j];
a[j]--;
}
ranges::sort(a, [&](int x, int y) {
return tin[x] < tin[y];
});
for (int j = 0; j < s; j++) {
int x = (j + 1) % s;
update(a[j], a[x]);
}
}
dfs(0, 0);
vector<int> ans;
for (int i = 0; i < n; i++) {
if (t[i] >= 2 * k) {
for (auto [j, pos] : g[i]) {
if (j == to[i][0]) {
ans.push_back(pos);
}
}
}
}
cout << ans.size() << '\n';
for (auto i : ans) {
cout << i + 1 << ' ';
}
cout << '\n';
return 0;
}
