#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define sc second
#define ii pair<int ,int>
const int MXN = 1e5;
const int LG = 17;
int n , m , k;
vector<int> nadj[MXN + 5];
vector<ii> vex , adj[MXN + 5];
int root;
int in[MXN + 5] , out[MXN + 5] , timer , up[MXN + 5][LG + 2];
int dp[MXN + 5] , f[MXN + 5];
vector<int> ANS;
void dfs(int u,int par){
in[u] = ++timer;
up[u][0] = par;
for (int i = 1; i <= LG ; i++) up[u][i] = up[up[u][i - 1]][i - 1];
for (ii v : adj[u]){
if (v.fi == par) continue;
dfs(v.fi , u);
}
out[u] = timer;
}
bool isAnc(int u,int v){
return (in[u] <= in[v] and out[v] <= out[u]);
}
int lca(int u,int v){
if (isAnc(u , v)) return u;
if (isAnc(v , u)) return v;
for (int i = LG ;i >= 0; i--){
if (!isAnc(up[u][i] , v)) u = up[u][i];
}
return up[u][0];
}
void build(){
stack<int> s;
for (ii v : vex){
while (!s.empty() and !isAnc(s.top() , v.sc)){
s.pop();
}
if (!s.empty()){
nadj[v.sc].emplace_back(s.top());
nadj[s.top()].emplace_back(v.sc);
}
s.push(v.sc);
}
}
void dfs1(int u,int par){
f[u] = 1;
for (int v : nadj[u]){
if (v == par) continue;
dfs1(v , u);
f[u] += f[v];
}
if (u == par) f[u] *= -1;
else{
f[u] -= nadj[u].size() - 1;
}
//cout << u <<' ' << f[u] <<'\n';
dp[u] += f[u];
}
void dfs2(int u,int par){
for (ii v : adj[u]){
if (v.fi == par) continue;
dfs2(v.fi , u);
dp[u] += dp[v.fi];
if (dp[v.fi] >= k) {
ANS.emplace_back(v.sc);
}
}
}
signed main(){
cin.tie(0)->ios_base::sync_with_stdio(0);
// freopen("SPEED.INP" , "r" , stdin);
// freopen("SPEED.OUT" , "w" , stdout);
cin >> n >> m >> k;
for (int i = 1; i < n ;i++){
int u , v; cin >> u >> v;
adj[u].emplace_back(v , i);
adj[v].emplace_back(u , i);
}
dfs(1 , 1);
for (int i = 1; i <= m ;i++){
int s; cin >> s;
for (int j = 1; j <= s ; j++){
int u; cin >> u;
vex.emplace_back(in[u] , u);
}
sort(vex.begin() , vex.end());
for (int j = 0; j + 1 < s ; j++){
int u = lca(vex[j].sc , vex[j + 1].sc);
vex.emplace_back(in[u] , u);
}
sort(vex.begin() , vex.end());
vex.resize(unique(vex.begin() , vex.end()) - vex.begin());
build();
dfs1(vex[0].sc , vex[0].sc);
for (ii v : vex){
nadj[v.sc].clear();
f[v.sc] = 0;
}
vex.clear();
}
dfs2(1 , 1);
sort(ANS.begin() , ANS.end());
cout << ANS.size() <<'\n';
for (int u : ANS) cout << u <<' ';
}
