#include <bits/stdc++.h>
using namespace std;
//#pragma GCC optimize ("O3")
//#pragma GCC target ("sse4")
#define endl "\n"
typedef long long ll;
template<class T, class T2> inline ostream &operator <<(ostream &out, const pair<T, T2> &x) { out << x.first << " " << x.second; return out;}
template<class T, class T2> inline istream &operator >>(istream &in, pair<T, T2> &x) { in >> x.first >> x.second; return in;}
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
const ll mod = 1e9 + 7;
#ifndef LOCAL
#define cerr if(false) cerr
#endif
const int MAX_N = 1e5 + 10, MAX_LOG = 20;;
vector<pair<int, int> > g[MAX_N];
int par[MAX_N][MAX_LOG];
int d[MAX_N];
int ind[MAX_N], cnt[MAX_N];
vector<int> ans;
int n, m, k;
void dfs(int x, int p) {
par[x][0] = p;
for(int i = 1; i < MAX_LOG; i ++) {
par[x][i] = par[par[x][i - 1]][i - 1];
}
d[x] = d[p] + 1;
for(auto it : g[x]) {
if(it.first == p) {continue;}
ind[it.first] = it.second;
dfs(it.first, x);
}
}
int lca(int a, int b) {
if(d[a] < d[b]) {swap(a, b);}
for(int i = MAX_LOG - 1; i >= 0; i --) {
if(d[par[a][i]] >= d[b]) {
a = par[a][i];
}
}
if(a == b) {return a;}
for(int i = 0; i < MAX_LOG; i ++) {
if(par[a][i] != par[b][i]) {
a = par[a][i];
b = par[b][i];
}
}
return par[a][0];
}
int calc(int x, int p) {
int now = cnt[x];
for(auto it : g[x]) {
if(it.first == p) {continue;}
now += calc(it.first, x);
}
if(now >= k) {
ans.push_back(ind[x]);
}
return now;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> m >> k;
for(int i = 0; i < n - 1; i ++) {
int a, b;
cin >> a >> b;
g[a].push_back({b, i + 1});
g[b].push_back({a, i + 1});
}
dfs(1, 0);
for(int i = 0; i < m; i ++) {
int lst;
cin >> lst;
vector<int> a(lst);
for(int j = 0; j < lst; j ++) {
cin >> a[j];
for(int small = 0; small < j; small ++) {
int l = lca(a[j], a[small]);
cnt[a[j]] ++;
cnt[a[small]] ++;
cnt[l] -= 2;
}
}
}
calc(1, 0);
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
for(auto it : ans) {
cout << it << " ";
}
return 0;
}
