#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(),v.rend()
#define pb push_back
#define sz(a) (int)a.size()
const int N = 1e5 + 5, K = 20;
vector<int> adj[N];
int jump[N][K], depth[N], tin[N], tt = 0, cnt[N];
void get_parents(int u, int par) {
jump[u][0] = par;
tin[u] = tt++;
for(int v: adj[u]) {
if(v == par) continue;
depth[v] = depth[u] + 1;
get_parents(v, u);
}
}
int lca(int a, int b) {
if(depth[a] < depth[b]) swap(a, b);
for(int i = K - 1; i >= 0; --i) {
if(depth[jump[a][i]] >= depth[b]) a = jump[a][i];
}
if(a == b) return a;
for(int i = K - 1; i >= 0; --i) {
if(jump[a][i] != jump[b][i]) {
a = jump[a][i];
b = jump[b][i];
}
}
return jump[a][0];
}
void dfs(int u, int par) {
for(int v: adj[u]) {
if(v == par) continue;
dfs(v, u);
cnt[u] += cnt[v];
}
}
void solve() {
int n, m, k; cin >> n >> m >> k;
map<pair<int, int>, int> mp;
for(int i = 0; i < n - 1; ++i) {
int u, v; cin >> u >> v; --u, --v;
adj[u].pb(v);
adj[v].pb(u);
mp[{u, v}] = mp[{v, u}] = i;
}
get_parents(0, 0);
for(int j = 1; j < K; ++j) {
for(int i = 0; i < n; ++i) {
jump[i][j] = jump[jump[i][j - 1]][j - 1];
}
}
while(m--) {
int len; cin >> len;
vector<int> a(len);
for(int i = 0; i < len; ++i) {
cin >> a[i]; --a[i];
}
sort(all(a), [&](int i, int j){return tin[i] < tin[j];});
vector<int> nodes = a;
for(int i = 0; i + 1 < len; ++i) {
nodes.pb(lca(a[i], a[i + 1]));
}
sort(all(nodes), [&](int i, int j){return tin[i] < tin[j];});
nodes.erase(unique(all(nodes)), nodes.end());
stack<int> st;
st.push(nodes[0]);
for(int i = 1; i < sz(nodes); ++i) {
while(lca(st.top(), nodes[i]) != st.top()) st.pop();
++cnt[nodes[i]];
--cnt[st.top()];
st.push(nodes[i]);
}
}
dfs(0, -1);
vector<int> v;
for(int i = 0; i < n; ++i) {
if(cnt[i] >= k) {
v.pb(mp[{i, jump[i][0]}]);
}
}
sort(all(v));
cout << sz(v) << "\n";
for(auto x: v) cout << x + 1 << " ";
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int t = 1;
//cin >> t;
while(t--) {
solve();
}
}
