// Author: 4uckd3v - Nguyen Cao Duc
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
const int MAX_N = 3e5;
const int MOD = 1e9 + 7;
int n, m, k, lg, timer;
int up[MAX_N + 5][20], tin[MAX_N + 5], tout[MAX_N + 5];
vector<int> queries[MAX_N + 5];
vector<ii> adj[MAX_N + 5];
void dfs(int u, int p) {
tin[u] = ++timer;
up[u][0] = p;
for (int i = 1; i <= lg; i++)
up[u][i] = up[up[u][i - 1]][i - 1];
for (ii e : adj[u]) {
int v = e.first;
if (v == p) continue;
dfs(v, u);
};
tout[u] = ++timer;
};
bool isAncestor(int u, int v) {
return tin[u] <= tin[v] && tout[u] >= tout[v];
};
int __lca(int u, int v) {
if (isAncestor(u, v)) return u;
if (isAncestor(v, u)) return v;
for (int i = lg; i >= 0; i--)
if (!isAncestor(up[u][i], v))
u = up[u][i];
return up[u][0];
};
namespace SUBTASK_1 {
const int N = 1e4;
bool mark[N + 5];
int ans[N + 5];
bool dfs(int u, int par) {
bool ok = mark[u];
for (ii e : adj[u]) {
int v = e.first, id = e.second;
if (v == par) continue;
if (dfs(v, u)) ok = true, ans[id]++;
};
return ok;
};
void Solve() {
for (int i = 0; i < m; i++) {
int lca = -1;
for (int u : queries[i]) {
if (lca == -1)
lca = u;
else
lca = __lca(lca, u);
mark[u] = true;
};
dfs(lca, up[lca][0]);
for (int u : queries[i]) mark[u] = false;
};
vector<int> edgesId;
for (int i = 1; i < n; i++) {
if (ans[i] >= k) edgesId.push_back(i);
};
cout << edgesId.size() << '\n';
for (int id : edgesId) cout << id << ' ';
cout << '\n';
}
} // namespace SUBTASK_1
namespace SUBTASK_2 {
const int N = MAX_N;
int dp[N + 5];
vector<int> edgesId;
bool checkSubtask() {
for (int i = 0; i < m; i++) {
if (queries[i].size() > 2) return false;
};
return true;
};
void dfs(int u, int par) {
for (ii e : adj[u]) {
int v = e.first, id = e.second;
if (v == par) continue;
dfs(v, u);
dp[u] += dp[v];
if (dp[v] >= k) edgesId.push_back(id);
};
}
void Solve() {
for (int i = 0; i < m; i++) {
if (queries[i].size() < 2) continue;
int u = queries[i][0], v = queries[i][1];
dp[u]++, dp[v]++;
dp[__lca(u, v)] -= 2;
};
dfs(1, 1);
sort(edgesId.begin(), edgesId.end());
cout << edgesId.size() << '\n';
for (int id : edgesId) cout << id << ' ';
cout << '\n';
};
}; // namespace SUBTASK_2
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
if (fopen("MAIN.INP", "r")) {
freopen("MAIN.INP", "r", stdin);
freopen("MAIN.OUT", "w", stdout);
};
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
adj[u].push_back(ii(v, i));
adj[v].push_back(ii(u, i));
}
lg = ceil(log2(n));
dfs(1, 1);
for (int i = 0; i < m; i++) {
int sz;
cin >> sz;
queries[i].resize(sz);
for (int &u : queries[i]) cin >> u;
};
if (SUBTASK_2::checkSubtask())
return SUBTASK_2::Solve(), 0;
SUBTASK_1::Solve();
};
