#include <bits/stdc++.h>
using namespace std;
void print() { cerr << '\n'; }
template<typename T, typename... Args>
void print(T first, Args... rest) {
cerr << first << ' ';
print(rest...);
}
const int li = 2e5 + 5;
int n, m, k;
vector<pair<int, int>> graph[li];
int tin[li], tout[li], timer = 0, anc[li][20], p_edge[li];
int chosen[li], bit[li];
void dfs(int node = 1, int parent = 0) {
tin[node] = ++timer;
for (int i = 1; i < 20; i++) anc[node][i] = anc[anc[node][i - 1]][i - 1];
for (pair<int, int> i : graph[node]) {
if (i.first != parent) {
anc[i.first][0] = node;
p_edge[i.first] = i.second;
dfs(i.first, node);
}
}
tout[node] = timer;
}
bool is_ancestor(int a, int b) { return (tin[a] <= tin[b] && tout[a] >= tout[b]); }
int lca(int a, int b) {
if (is_ancestor(a, b)) return a;
for (int i=19; ~i; i--) {
if (anc[a][i] && !is_ancestor(anc[a][i], b)) a = anc[a][i];
}
return anc[a][0];
}
void update(int pos, int val) {
for (; pos <= n; pos += (pos & (-pos))) bit[pos] += val;
}
int query(int a, int b) {
int ans = 0;
for (; b; b -= (b & (-b))) ans += bit[b];
for (a--; a; a -= (a & (-a))) ans -= bit[a];
return ans;
}
signed main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m >> k;
for (int i=1, a, b; i<=n-1; i++) {
cin >> a >> b;
graph[a].push_back({b, i});
graph[b].push_back({a, i});
}
dfs();
while (m--) {
// cout << " *" << m << "\n";
int s, l;
cin >> s;
for (int i=0; i<s; i++) cin >> chosen[i];
sort(chosen, chosen + s, [](int A, int B) { return tin[A] < tin[B]; });
chosen[s] = chosen[0];
for (int i = 0; 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;
for (int i=2; i<=n; i++)
if (query(tin[i], tout[i]) >= 2 * k) ans.push_back(p_edge[i]);
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (int i : ans) cout << i << ' ';
return 0;
}
