#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> ii;
int n,m,k;
vector<vector<ii>> adj; // viz e qual aresta
vector<vector<int>> sparse;
vector<int> tin,tout;
vector<int> node, res; // guarda a soma;
int t = 0;
void dfs(int x, int ant){
t++;
tin[x] = t;
for(auto [a,b] : adj[x]){
if(a == ant) continue;
sparse[0][a] = x;
dfs(a,x);
}
tout[x] = t;
return;
}
void build(){
for(int i=1; i<25; i++) for(int j = 0; j<n; j++){
sparse[i][j] = sparse[i-1][sparse[i-1][j]];
}
return;
}
bool anc(int a, int b){// a é pai de b
if(tin[a] <= tin[b] and tout[a] >= tout[b]) return true;
return false;
}
int lca(int a,int b){
if(anc(a,b)) return a;
if(anc(b,a)) return b;
for(int i=24; i>=0; i--){
int novo = sparse[i][a];
if(anc(novo, b)) continue;
a = novo;
}
return sparse[0][a];
}
bool cmp(int a, int b){
if(tout[a] != tout[b]) return tout[a] < tout[b];
else return tin[a] > tin[b];
}
int dfs2(int x, int ant, int aresta){
int sum = node[x];
for(auto [a,b]: adj[x]){
if(a == ant) continue;
sum += dfs2(a,x,b);
}
if(sum >= k) res.push_back(aresta);
return sum;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n>> m >> k;
adj.resize(n); tin.resize(n+3), tout.resize(n+3);
node.assign(n, 0);
sparse.assign(25, vector<int>(n,0));
for(int i=0; i<n-1; i++){
int a,b; cin >> a >> b; a--; b--;
adj[a].push_back({b, i+1});
adj[b].push_back({a,i+1});
}
dfs(0,0);
build();
for(int i=0; i<m; i++){
int s; cin >> s;
vector<int> v(s);
int paiComum = -1;
for(int j=0; j<s; j++){
cin >> v[j];
v[j]--;
if(paiComum == -1) paiComum = v[j];
else{paiComum = lca(paiComum, v[j]);}
}
//cout <<"lca "<< paiComum << endl;
sort(v.begin(), v.end(),cmp);
for(int j= 0; j< s; j++){
if(j == 0){
node[v[j]] += 1;
node[paiComum] -= 1;
}
else{
int ant = v[j-1];
if(anc(v[j], ant)) continue;
else{
node[v[j]] += 1;
int outro = lca(v[j], ant);
node[outro]-=1;
// cout << v[j] << endl;
}
}
}
}
dfs2(0,0,0);
sort(res.begin(), res.end());
cout << res.size()<< endl;
for(int i=0; i<res.size(); i++){
if(i) cout <<' ';
cout << res[i];
}
cout << endl;
}
