#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e5 + 5;
vector<pair<int, int>> G[MAX_N];
map<int, int> cnt[MAX_N];
int S[MAX_N], bad[MAX_N];
vector<int> ans;
void DFS(int u, int p, int k) {
for (auto [key, value] : cnt[u]) {
bad[u] += value == S[u];
}
for (auto [v, i] : G[u]) {
if (i != p) {
DFS(v, i, k);
if (cnt[u].size() < cnt[v].size()) {
swap(cnt[u], cnt[v]);
swap(bad[u], bad[v]);
}
for (auto [key, value] : cnt[v]) {
cnt[u][key] += value;
bad[u] += cnt[u][key] == S[key];
}
}
}
if ((int)cnt[u].size() - bad[u] >= k) {
ans.push_back(p);
}
}
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
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});
}
for (int i = 0; i < M; i++) {
cin >> S[i];
for (int j = 0; j < S[i]; j++) {
int v;
cin >> v;
v--;
cnt[v][i]++;
}
}
DFS(0, -1, K);
int L = (int)ans.size();
cout << L << "\n";
for (int i = 0; i < L; i++) {
cout << 1 + ans[i] << " \n"[i + 1 == L];
}
}
