#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define MOD 1000000007
#define inf 1e18
#define fi first
#define se second
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define sz(a) ((int)(a).size())
#define endl '\n'
#define pi 3.14159265359
#define TASKNAME "railway"
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
using namespace std;
typedef pair<int,int> ii;
typedef pair<int,ii> iii;
typedef vector<int> vi;
const int MAXN = 3e5 + 9;
vector<int> g[MAXN];
struct Query{
int num;
vector<int> QueryVert;
} Q[MAXN];
int n, m, k, S;
ii edge[MAXN], par[MAXN];
int QueryVert[MAXN], depth[MAXN], pre[MAXN], FreqCount[MAXN];
namespace subtask2{
bool checkSubtask2(){
return true;
}
vector<int> etour = {0};
vector<int> virtualTree[MAXN];
int in[MAXN], out[MAXN], FreqCount[MAXN], dfsTime = 0;
ii P[MAXN * 2][21];
void dfs(int u, int p){
etour.pb(u);
in[u] = ++dfsTime;
for(auto id: g[u]){
int v = edge[id].se + edge[id].fi - u;
if (v == p) continue;
depth[v] = depth[u] + 1;
par[v] = {u, id};
dfs(v, u);
etour.pb(u);
dfsTime++;
}
out[u] = dfsTime;
}
ii getrange(int l, int r){
int x = log2(r - l + 1);
return min(P[l][x], P[r - (1 << x) + 1][x]);
}
ii lca(int u, int v){
return getrange(min(in[u], in[v]), max(in[u], in[v]));
}
bool inTree(int u, int v){ //Check if vertice v lie in the subtree of the vertice u
return in[v] >= in[u] and in[v] <= out[u];
}
void VirtualTree(int num, vector<int> &Vertice){
sort(Vertice.begin(), Vertice.end(), [&](const int &u, const int &v){
return in[u] < in[v];
});
for(int i = 0; i < num - 1; i++){
int u = Vertice[i];
int v = Vertice[i + 1];
ii acs = lca(u, v);
Vertice.pb(acs.se);
}
sort(Vertice.begin(), Vertice.end(), [&](const int &u, const int &v){
return in[u] < in[v];
});
Vertice.erase(unique(Vertice.begin(), Vertice.end()), Vertice.end());
vector<int> curStack;
for(int i = 0; i < Vertice.size(); i++){
if (curStack.size() == 0) curStack.pb(Vertice[i]);
else{
int x = curStack.back();
while(curStack.size() > 0 and !inTree(curStack.back(), Vertice[i])) {
curStack.pop_back();
}
pre[curStack.back()]--;
pre[Vertice[i]]++;
curStack.pb(Vertice[i]);
}
}
}
void CountAnswer(int u, int p){
for(auto id: g[u]){
int v = edge[id].se + edge[id].fi - u;
if (v == p) continue;
CountAnswer(v, u);
FreqCount[id] += pre[v];
pre[u] += pre[v];
}
}
void solveSubtask2(){
//preDfs
dfs(1, -1);
//Sparse Table For LCA
for(int i = 1; i < etour.size(); i++){
P[i][0] = ii(depth[etour[i]], etour[i]);
}
for(int i = 1; i <= 18; i++){
for(int j = 1; j + (1 << i) - 1 < etour.size(); j++){
P[j][i] = min(P[j][i - 1], P[j + (1 << (i - 1))][i - 1]);
}
}
//Handle Queries
for(int i = 1; i <= m; i++){
int num = Q[i].num;
VirtualTree(num, Q[i].QueryVert); //Using Virtual Tree to handle Queries.
}
CountAnswer(1, -1);
vector<int> ans;
for(int i = 1; i < n; i++){
if (FreqCount[i] >= k) ans.pb(i);
}
cout << ans.size() << endl;
for(auto x: ans){
cout << x << ' ';
}
cout << endl;
}
}
main()
{
fast;
if (fopen(TASKNAME".inp","r")){
freopen(TASKNAME".inp","r",stdin);
freopen(TASKNAME".out","w",stdout);
}
cin >> n >> m >> k;
for(int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
g[u].pb(i);
g[v].pb(i);
edge[i] = {u, v};
}
for(int i = 1; i <= m; i++){
cin >> Q[i].num;
for(int j = 0; j < Q[i].num; j++){
int x;
cin >> x;
Q[i].QueryVert.pb(x);
}
}
if (subtask2::checkSubtask2()) return subtask2::solveSubtask2(), 0;
}
/**
Warning:
- MLE / TLE?
- Gioi han mang?
- Gia tri max phai luon gan cho -INF
- long long co can thiet khong?
- tran mang.
- code can than hon
- Nho sinh test de tranh RTE / TLE
--> Coi lai truoc khi nop
**/
