#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define pb(e) push_back(e)
#define sv(a) sort(a.begin(),a.end())
#define sa(a,n) sort(a,a+n)
#define mp(a,b) make_pair(a,b)
#define vf first
#define vs second
#define ar array
#define all(x) x.begin(),x.end()
const int inf = 0x3f3f3f3f;
const int mod = 1000000007;
const double PI=3.14159265358979323846264338327950288419716939937510582097494459230;
bool remender(ll a , ll b){return a%b;}
const int N = 100002 , l = 25;
int n , m , k;
vector<pair<int,int>> adj[N];
int cnt[N],timer,tin[N], tout[N],up[N][l + 5];
vector<int> ans;
void dfs(int v, int p){
tin[v] = ++timer;
up[v][0] = p;
for (int i = 1; i <= l; ++i)
up[v][i] = up[up[v][i-1]][i-1];
for (auto &[u,ldonewjfjiwjjfosfojg] : adj[v]) {
if (u != p)
dfs(u, v);
}
tout[v] = ++timer;
}
bool is_ancestor(int u, int v){
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v){
if (is_ancestor(u, v))
return u;
if (is_ancestor(v, u))
return v;
for (int i = l; i >= 0; --i) {
if (!is_ancestor(up[u][i], v))
u = up[u][i];
}
return up[u][0];
}
bool cmp(int x , int y){
return tin[x] < tin[y];
}
void dfs1(int node , int par = -1){
for(auto &[i,idx] : adj[node]){
if(i!=par){
dfs1(i,node);
if(cnt[i] >= 2 * k)ans.pb(idx);
cnt[node] += cnt[i];
}
}
}
void solve(){
cin >> n >> m >> k;
for(int i = 1; i < n; i++){
int u , v;
cin >> u >> v;
adj[u].pb(mp(v,i));
adj[v].pb(mp(u,i));
}
timer = 0;
dfs(1,1);
memset(cnt,0,sizeof cnt);
for(int i = 0; i < m; i++){
int s;
cin >> s;
int arr[s];
for(int j = 0; j < s; j++){
cin >> arr[j];
}
sort(arr,arr+s,cmp);
for(int j = 0; j < s; j++){
int lc = lca(arr[j],arr[(j + 1) % s]);
cnt[lc]-=2;
cnt[arr[j]]++;
cnt[arr[(j + 1) % s]]++;
}
}
dfs1(1);
sv(ans);
cout << ans.size() << '\n';
for(int i : ans)cout << i << ' ';
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//int t;cin >> t;while(t--)
solve();
return 0;
}
