// `Be name khoda` //
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
#define all(x) x.begin(), x.end()
#define fi first
#define se second
const int maxn5 = 2e5 + 10;
int k, num = 0, cnt[maxn5], lim[maxn5];
int st[maxn5], ft[maxn5], ver[maxn5], ti = -1;
int sz[maxn5], big[maxn5], pared[maxn5];
vector <int> ans, req[maxn5];
vector <pair<int, int>> adj[maxn5];
inline void upd(int a, int val){
//cout << "updating " << a << ' ' << val << endl;
if(cnt[a] > 0 && cnt[a] < lim[a])
num--;
cnt[a] += val;
if(cnt[a] > 0 && cnt[a] < lim[a])
num++;
//cout << "final value of " << num << ' ' << cnt[a] << ' ' << lim[a] << endl;
}
inline void dfs_det(int v){
sz[v] = 1;
big[v] = -1;
st[v] = ++ti;
ver[ti] = v;
for(auto [u, id] : adj[v]) if(id != pared[v]){
pared[u] = id;
dfs_det(u);
sz[v] += sz[u];
if(big[v] == -1 || sz[big[v]] <= sz[u])
big[v] = u;
}
ft[v] = ti;
return;
}
inline void dfs_gooni(int v, bool keep){
for(auto [u, id] : adj[v]) if(u != big[v] && id != pared[v])
dfs_gooni(u, false);
if(big[v] == -1){
//cout << "here barg " << v << endl;
for(auto u : req[v])
upd(u, 1);
if(num >= k)
ans.pb(pared[v]);
//cout << "having " << num << endl;
if(keep)
return;
for(auto u : req[v])
upd(u, -1);
return;
}
dfs_gooni(big[v], true);
for(auto u : req[v])
upd(u, 1);
for(auto [u, id] : adj[v]) if(u != big[v] && id != pared[v]) for(int i = st[u]; i <= ft[u]; i++)
for(auto z : req[ver[i]])
upd(z, 1);
//cout << "ok " << v << ' ' << big[v] << ' '<< num << endl;
if(num >= k)
ans.pb(pared[v]);
if(keep)
return;
for(int i = st[v]; i <= ft[v]; i++) for(auto u : req[ver[i]])
upd(u, -1);
return;
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n, m; cin >> n >> m >> k;
for(int i = 0; i < n - 1; i++){
int a, b; cin >> a >> b;
a--; b--;
adj[a].pb({b, i});
adj[b].pb({a, i});
}
for(int i = 0; i < m; i++){
int l; cin >> l;
lim[i] = l;
while(l--){
int a; cin >> a; a--;
req[a].pb(i);
}
}
pared[0] = n + 1;
dfs_det(0);
dfs_gooni(0, true);
cout << ans.size() << endl;
sort(all(ans));
for(auto u : ans)
cout << u + 1 << ' ';
cout << endl;
}
