#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (100005)
ll N,M,K;
vector<pair<ll,ll> > v[MAXN]; //node b, index of edge
vector<ll> ans;
set<pair<ll,ll> > s[MAXN];
ll parent[20][MAXN], depth[MAXN], dist[MAXN];
bool visited[MAXN];
void distdfs(ll x){
visited[x] = 1;
for(auto u : v[x]){
if(visited[u.first] == 0){
dist[u.first] = dist[x] + 1;
visited[u.first] = 1;
distdfs(u.first);
}
}
}
void dfs1(ll x,ll nodeparent,ll nodedepth){
parent[0][x] = nodeparent;
depth[x] = nodedepth;
for(ll i = 0;i < v[x].size();i++){
if(v[x][i].first != nodeparent){
dfs1(v[x][i].first,x,nodedepth + 1);
}
}
}
void lcainit(){
for(ll i = 1;i < 20;i++){
for(ll j = 0;j < N;j++){
parent[i][j] = parent[i - 1][parent[i - 1][j]];
}
}
}
ll lca(ll u,ll v){
if(depth[u] > depth[v]){
swap(u,v);
}
ll diff = depth[v] - depth[u];
for(ll i = 0;i < 20;i++){
if(diff & (1<<i)){
v = parent[i][v];
}
}
if(u == v){
return u;
}
for(ll i = 19;i >= 0;i--){
if(parent[i][u] != parent[i][v]){
u = parent[i][u];
v = parent[i][v];
}
}
return parent[0][u];
}
void dfs2(ll x,ll p){
ll parentedge = -1;
for(auto u : v[x]){
if(u.first != p){
dfs2(u.first,x);
if(s[u.first].size() > s[x].size()) swap(s[u.first],s[x]); //swap sets is O(1)
//swapping 2 sets, vectors, maps are O(1) so use these data structures
//for pbds, it is a bit different syntax: a.swap(b) is O(1)
s[x].insert(s[u.first].begin(),s[u.first].end());
}else{
parentedge = u.second;
}
}
while(!s[x].empty() && s[x].begin()->first == -1 * depth[x]){
s[x].erase(s[x].begin());
}
if(s[x].size() >= K && parentedge != -1){
ans.push_back(parentedge);
}
}
int main() {
ios_base::sync_with_stdio(false);cin.tie(0);
cin>>N>>M>>K;
for(ll i = 0;i < N - 1;i++){
ll a,b;
cin>>a>>b;
a--, b--;
v[a].push_back({b,i});
v[b].push_back({a,i});
}
dist[0] = 0;
visited[0] = 1;
distdfs(0);
dfs1(0,0,0);
lcainit();
for(ll i = 0;i < M;i++){
ll S;
cin>>S;
ll LCA = -1;
ll A[S];
for(ll j = 0;j < S;j++){
cin>>A[j];
A[j]--;
if(j == 0){
LCA = A[j];
}else{
LCA = lca(LCA,A[j]);
}
}
for(ll j = 0;j < S;j++){
s[A[j]].insert({-depth[LCA],i});
}
}
dfs2(0,-1);
sort(ans.begin(),ans.end());
cout<<ans.size()<<'\n';
for(auto u : ans){
cout<<u + 1<<" ";
}
cout<<'\n';
}
