#include <bits/stdc++.h>
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int,int> vii;
vector<pair<map<int,int>*, int>> things;
vector<vector<vii>> G;
vi par_num;
vi ans;
vvi colors;
vi S;
int k;
void dfs(int node, int p) {
int d = 0;
int m = -1;
int j = -1; // initialize heavy-child index
// find heavy child
for (int i = 0; i < (int)G[node].size(); i++) {
if (G[node][i].first == p) {
par_num[node] = G[node][i].second;
continue;
}
d++;
dfs(G[node][i].first, node);
// defensive assert: child map must exist
assert(things[G[node][i].first].first != nullptr);
if ((int)things[G[node][i].first].first->size() > m) {
m = (int)things[G[node][i].first].first->size();
j = i;
}
}
if (d == 0) {
// leaf: allocate new map
things[node].first = new map<int,int>();
for (int c : colors[node]) {
(*things[node].first)[c]++;
}
if ((int)things[node].first->size()>= k && node != 0)
ans.push_back(par_num[node]);
return;
}
// if no heavy child chosen (defensive), pick first non-parent
if (j == -1) {
for (int i = 0; i < (int)G[node].size(); ++i) {
if (G[node][i].first != p) { j = i; break; }
}
}
// inherit heavy child's map
things[node] = things[G[node][j].first];
// add current node's colors
for (int c : colors[node]) {
auto &mp = *things[node].first;
mp[c]++;
if (mp[c] == S[c]) things[node].second++;
}
// merge other children
for (int i = 0; i < (int)G[node].size(); ++i) {
if (i == j || G[node][i].first == p) continue;
int child = G[node][i].first;
things[node].second += things[child].second;
for (auto &kv : *things[child].first) {
int color = kv.first;
int count = kv.second;
auto &mp = *things[node].first;
int before = mp[color];
mp[color] += count;
if (before < S[color] && mp[color] >= S[color]) things[node].second++;
}
}
if (node != 0 && (int)things[node].first->size() - things[node].second >= k)
ans.push_back(par_num[node]);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m;
cin >> n >> m >> k;
colors.assign(n, {});
G.assign(n, {});
par_num.assign(n, 0);
things.assign(n, {nullptr, 0});
S.assign(m, 0);
for (int i = 0; i < n-1; i++) {
int a,b;
cin >> a >> b;
--a; --b;
G[a].push_back({b, i+1});
G[b].push_back({a, i+1});
}
for (int i = 0; i < m; i++) {
int s; cin >> s;
S[i] = s;
for (int j = 0; j < s; j++) {
int a; cin >> a; --a;
colors[a].push_back(i);
}
}
dfs(0, -1);
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (int x : ans) cout << x << " ";
cout << "\n";
// cleanup: delete unique maps
unordered_set<map<int,int>*> uniq;
for (auto &p : things) if (p.first) uniq.insert(p.first);
for (auto mp : uniq) delete mp;
return 0;
}
