#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define per(i, a, b) for (int i = b - 1; i >= (a); --i)
#define trav(a, x) for (auto &a : x)
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define pb push_back
#define umap unordered_map
#define uset unordered_set
typedef pair<int, int> ii;
typedef pair<int, ii> iii;
typedef vector<int> vi;
typedef vector<ii> vii;
typedef vector<vi> vvi;
typedef long long ll;
const int INF = 1000000007;
int n, m, k, cnt[100001], layer[100001], curr;
vii graph[100001];
bool dfs(int u, int p) {
bool ret = (layer[u] == curr);
trav(edge, graph[u]) if (edge.first != p) {
if (dfs(edge.first, u)) ++cnt[edge.second], ret = 1;
}
return ret;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin.exceptions(cin.failbit);
memset(cnt, 0, sizeof(cnt));
memset(layer, -1, sizeof(layer));
cin >> n >> m >> k;
int a, b;
rep(i, 0, n - 1) {
cin >> a >> b;
graph[--a].emplace_back(--b, i);
graph[b].emplace_back(a, i);
}
rep(i, 0, m) {
int s, u;
curr = i;
cin >> s;
rep(j, 0, s) cin >> u, layer[u - 1] = i;
dfs(u - 1, u - 1);
}
vi ans;
rep(i, 0, n) {
if (k <= cnt[i]) ans.pb(i + 1);
}
cout << sz(ans) << endl;
trav(edge, ans) cout << edge << ' ';
cout << endl;
return 0;
}
