// IOI 2021
#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ends ' '
#define die(x) return cout << x << endl, 0
#define all(v) v.begin(), v.end()
#define sz(x) (int)(x.size())
void debug_out() { cerr << endl; }
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) { cerr << ends << H; debug_out(T...); }
#define debug(...) cerr << "{" << #__VA_ARGS__ << "}:", debug_out(__VA_ARGS__)
typedef long long ll;
typedef pair<int, int> pii;
const ll INF = 1e9;
const ll MOD = 1e9 + 7;
////////////////////////////////////////////////////////////////////
const int N = 1e5 + 5;
int k, SZ[N], S[N], C[N];
vector<int> M[N];
vector<pii> G[N];
vector<int> E;
int DFSZ(int v, int p = 0) {
SZ[v] = 1;
for (pii e : G[v]) if (e.second != p) SZ[v] += DFSZ(e.first, e.second);
return SZ[v];
}
void DFS(int v, int p, map<int, int> &mp) {
pii bigE = make_pair(0, 0);
for (pii e : G[v]) if (e.second != p && SZ[e.first] > SZ[bigE.first]) bigE = e;
if (bigE.first) DFS(bigE.first, bigE.second, mp), C[v] = C[bigE.first];
map<int, int> tmp;
for (pii e : G[v]) if (e.second != p && e != bigE) {
DFS(e.first, e.second, tmp);
for (pii m : tmp) {
mp[m.first] += m.second;
if (mp[m.first] == S[m.first]) C[v]++;
}
tmp.clear();
}
for (int m : M[v]) if (++mp[m] == S[m]) C[v]++;
if (k <= sz(mp) - C[v]) E.push_back(p);
}
int main() {
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
int n, m; cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int v, u; cin >> v >> u;
G[v].push_back(make_pair(u, i));
G[u].push_back(make_pair(v, i));
}
DFSZ(1);
for (int i = 1; i <= m; i++) {
cin >> S[i];
for (int j = 1; j <= S[i]; j++) {
int v; cin >> v;
M[v].push_back(i);
}
}
map<int, int> tmp;
DFS(1, 0, tmp);
sort(all(E));
cout << sz(E) << endl;
for (int e : E) cout << e << ends;
cout << endl;
return 0;
}
