// In the name of the God
#include <bits/stdc++.h>
#define ll long long
// #define int long long
#define pb push_back
#define F first
#define S second
#define mp make_pair
#define pii pair <int, int>
#define smin(x, y) (x) = min((x), (y))
#define smax(x, y) (x) = max((x), (y))
#define all(x) (x).begin(), (x).end()
using namespace std;
const int inf = 1e9+7;
const int mod = 998244353;
const int maxn = 1e5+5, lg = 17;
int n, m, k, t = 0, in[maxn], out[maxn], cnt[maxn], par[lg][maxn];
vector <int> vec;
vector <pii> adj[maxn];
bool cmp(int v, int u) {
return in[v] < in[u];
}
void dfs1(int v, int p) {
in[v] = t++;
par[0][v] = p;
for (int i = 1; i < lg; i++) par[i][v] = par[i-1][par[i-1][v]];
for (pii e : adj[v]) {
if (e.F != p) dfs1(e.F, v);
}
out[v] = t;
}
bool is(int v, int u) {
return in[v] <= in[u] and out[v] >= out[u];
}
int lca(int v, int u) {
if (is(v, u)) return v;
if (is(u, v)) return u;
for (int i = lg-1; i >= 0; i--) {
if (!is(par[i][v], u)) v = par[i][v];
}
return par[0][v];
}
void dfs2(int v, int p, int ed) {
for (pii e : adj[v]) {
if (e.F != p) {
dfs2(e.F, v, e.S);
cnt[v] += cnt[e.F];
}
}
if (cnt[v] >= k) vec.pb(ed);
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int v, u; cin >> v >> u;
adj[--v].pb(mp(--u, i));
adj[u].pb(mp(v, i));
}
dfs1(0, 0);
for (int i = 0; i < m; i++) {
int s; cin >> s;
for (int j = 0; j < s; j++) {
int v; cin >> v;
cnt[--v]++;
vec.pb(v);
}
sort(all(vec), cmp);
for (int i = 1; i < s; i++) cnt[lca(vec[i], vec[i-1])]--;
cnt[lca(vec[0], vec[s-1])]--;
vec.clear();
}
dfs2(0, 0, 0);
sort(all(vec));
cout << vec.size() << '\n';
for (int e : vec) cout << e << ' ';
cout << '\n';
return 0;
}
