#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
const int li = 1e5 + 5;
struct edge{ int v, id; };
int n, m, k, tin[li], tout[li], tick = 0, anc[li][21], p_edge[li];
vector<edge> adj[li];
void dfs(int node = 1, int par = 0) {
tin[node] = ++tick;
for (int i=1; i<=19; i++) anc[node][i] = anc[anc[node][i-1]][i-1];
for (edge& other : adj[node]) {
if (other.v == par) continue;
anc[other.v][0] = node;
p_edge[other.v] = other.id;
dfs(other.v, node);
}
tout[node] = tick;
}
bool is_anc(int a, int b) { return (tin[b] >= tin[a] && tout[b] <= tout[a]); }
int lca(int a, int b) {
if (is_anc(a, b)) return a;
for (int i=19; ~i; i--) if (anc[a][i] && !is_anc(anc[a][i], b)) a = anc[a][i];
return anc[a][0];
}
int fen[li];
void update(int pos, int val) { for (; pos <= n; pos += pos & (-pos)) fen[pos] += val; }
int query(int pos) { int ans = 0; for(;pos; pos -= pos & (-pos)) ans += fen[pos]; return ans; }
int get(int l, int r) { return query(r) - query(l - 1); }
int chosen[li];
signed main() {
cin >> n >> m >> k;
for (int i=1, u, v; i<=n-1; i++) {
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
dfs();
while (m--) {
int s;
cin >> s;
for (int i=1; i<=s; i++) cin >> chosen[i];
sort(chosen + 1, chosen + s + 1, [](int x, int y) { return tin[x] < tin[y]; });
chosen[s + 1] = chosen[1];
for (int i=1; i<=s; i++) {
int l = lca(chosen[i], chosen[i + 1]);
update(tin[chosen[i]], 1);
update(tin[chosen[i + 1]], 1);
update(tin[l], -2);
}
}
vector<int> ans;
k <<= 1;
for (int i=2; i<=n; i++) {
if (get(tin[i], tout[i]) >= k) ans.push_back(p_edge[i]);
}
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (int i : ans) cout << i << ' ';
}
