#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 1e5 + 5;
const int L = 20;
vector<int> adj[N];
int cur, dist[N], par[N], sp[N][L], val[N], intime[N];
void sp_table(int u){
sp[u][0] = par[u];
int power = 1;
for (int i = 1; i < L; i++){
power *= 2;
if (dist[u] < power) sp[u][i] = 0;
else sp[u][i] = sp[sp[u][i - 1]][i - 1];
}
}
void dfs(int u){
intime[u] = ++cur;
sp_table(u);
for (auto i : adj[u]){
if (par[u] != i){
dist[i] = dist[u] + 1;
par[i] = u;
dfs(i);
}
}
}
int kth_ancestor(int u, int k){
if (k == 0) return u;
int power = 1;
int ans = u;
for (int i = 0; i < L; i++){
if (k & power){
ans = sp[ans][i];
}
power *= 2;
}
return ans;
}
int LCA(int u, int v){
if (dist[u] > dist[v]) swap(u, v);
v = kth_ancestor(v, dist[v] - dist[u]);
if (u == v) return u;
for (int i = L - 1; i >= 0; i--){
if (sp[u][i] != sp[v][i]){
u = sp[u][i];
v = sp[v][i];
}
}
return par[v];
}
int ans, k;
map<pair<int, int>, int> E;
vector<int> op;
void dfs1(int u = 1){
for (auto v : adj[u]){
if (v == par[u]) continue;
dfs1(v);
val[u] += val[v];
}
if (val[u] >= k) {ans++;
op.push_back(E[{par[u], u}]);
}
}
signed main(){
int n, m; cin >> n >> m >> k;
for (int i = 1; i < n; i++){
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
E[{u, v}] = i;
E[{v, u}] = i;
}
dfs(1);
for (int i = 1; i <= m; i++){
int s; cin >> s;
vector<pair<int, int>> p;
for (int j = 1; j <= s; j++){
int x; cin >> x;
val[x]++;
p.push_back({intime[x], x});
}
sort(p.begin(), p.end());
for (int j = 1; j < s; j++){
int x = LCA(p[j].second, p[j - 1].second);
val[x]--;
}
val[LCA(p[0].second,p.back().second)]--;
}
dfs1();
cout << ans << endl;
sort(begin(op), end(op));
for (auto i : op) cout << i << ' ';
cout << endl;
}
