// In the name of God
#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define fi first
#define se second
#define mp make_pair
typedef long long ll;
const int N = 1e5 + 5, MOD = 1e9 + 7, L = 20;
int n, m, k;
vector<pair<int, int> > adj[N];
vector<int> ans;
int dp[N], tin[N], tout[N], up[N][L];
int T;
void dfs(int v, int p) {
up[v][0] = p;
for (int l = 1; l < L; l++)
up[v][l] = up[up[v][l - 1]][l - 1];
tin[v] = ++T;
for (auto [u, i] : adj[v]) {
if (u != p)
dfs(u, v);
}
tout[v] = ++T;
}
bool anc(int v, int u) {
return tin[v] <= tin[u] && tout[v] >= tin[u];
}
int lca(int v, int u) {
if (tin[v] > tin[u])
swap(v, u);
if (anc(v, u))
return v;
for (int l = L - 1; l >= 0; l--)
if (!anc(up[v][l], u))
v = up[v][l];
return up[v][0];
}
void dfs2(int v, int p, int e) {
for (auto [u, i] : adj[v]) {
if (u != p) {
dfs2(u, v, i);
dp[v] += dp[u];
}
}
if (dp[v] >= k)
ans.pb(e);
}
void solve() {
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int v, u; cin >> v >> u;
adj[v].pb(mp(u, i + 1)), adj[u].pb(mp(v, i + 1));
}
dfs(1, 0);
tout[0] = 1e9;
for (int i = 0; i < m; i++) {
int s; cin >> s;
vector<pair<int, int> > vec;
for (int j = 0; j < s; j++) {
int v; cin >> v;
vec.pb(mp(tin[v], v));
}
sort(vec.begin(), vec.end());
int l2 = vec[0].se;
for (int i = 1; i < s; i++) {
int l = lca(vec[i].se, vec[i - 1].se);
l2 = lca(l, l2);
dp[l]--;
dp[vec[i - 1].se]++;
}
dp[l2]--;
dp[vec.back().se]++;
}
dfs2(1, 0, 0);
cout << ans.size() << '\n';
sort(ans.begin(), ans.end());
for (auto x : ans)
cout << x << ' ';
cout << '\n';
}
int32_t main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
solve();
return 0;
}
