#include <bits/stdc++.h>
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define int long long
using namespace std;
const int LOG=24;
vector<vector<int>> neigh;
vector<vector<int>> clr_group;
vector<int> val;
vector<int> in;
vector<int> ans;
vector<vector<int>> parent;
vector<int> depth;
map<pair<int,int>,int> mp;
int n,m,k;
int timer=0;
int dfs(int x, int p){
int sm=val[x];
for (auto u : neigh[x])
{
if(u==p) continue;
sm+=dfs(u,x);
}
if(sm>=k){
ans.push_back(mp[{x,p}]);
}
return sm;
}
int lca(int a, int b){
if(depth[b]<depth[a]) swap(a,b);
int d=depth[b]-depth[a];
for (int j = LOG-1; j >= 0; j--)
{
if(d&(1<<j)) b=parent[b][j];
}
if(a==b) return a;
for (int j = LOG-1; j >= 0; j--)
{
if(parent[a][j]!=parent[b][j]) b=parent[b][j], a=parent[a][j];
}
return parent[a][0];
}
void setup_lca(int x, int p){
parent[x][0]=p;
in[x]=timer++;
for (int j = 1; j < LOG; j++) parent[x][j]=parent[parent[x][j-1]][j-1];
for (auto u : neigh[x])
{
if(u==p) continue;
depth[u]=depth[x]+1;
setup_lca(u,x);
}
return;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> m >> k;
neigh.resize(n);
parent.resize(n,vector<int>(LOG,0));
depth.resize(n);
val.resize(n,0);
in.resize(n);
clr_group.resize(m);
for (int i = 0; i < n-1; i++)
{
int a,b; cin >> a >> b;
neigh[a-1].push_back(b-1);
neigh[b-1].push_back(a-1);
mp[{a-1,b-1}]=i;
mp[{b-1,a-1}]=i;
}
for (int i = 0; i < m; i++)
{
int nm; cin >> nm;
while(nm--){
int a; cin >> a; a--;
clr_group[i].push_back(a);
}
}
setup_lca(0,0);
for (int i = 0; i < m; i++)
{
sort(all(clr_group[i]),[](int a, int b){ return in[a]<in[b]; });
for (int j = 0; j < sz(clr_group[i]); j++)
{
val[clr_group[i][j]]++;
val[lca(clr_group[i][(j-1+sz(clr_group[i]))%sz(clr_group[i])],clr_group[i][j])]--;
}
}
dfs(0,0);
sort(all(ans));
cout << sz(ans) << "\n";
for (auto u : ans) cout << u+1 << " ";
return 0;
}
