#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
const int MAXN = 1e5 + 5;
const int MAXD = 18;
int N, M, K, LCA[MAXN][MAXD], depth[MAXN];
vector<pair<int, int> > adj[MAXN];
vector<int> add[MAXN], sub[MAXN], ans;
void dfs(int i, int p){
for(auto it: adj[i]) if(it.first != p){
depth[it.first] = depth[i] + 1;
LCA[it.first][0] = i;
dfs(it.first, i);
}
}
set<int> dfs2(int i, int p, int from){
set<int> curr;
for(auto it: adj[i]) if(it.first != p){
set<int> temp = dfs2(it.first, i, it.second);
if(temp.size() > curr.size())
swap(temp, curr);
curr.insert(temp.begin(), temp.end());
}
for(int x: add[i]){
curr.insert(x);
}
for(int x: sub[i]){
curr.erase(x);
}
if((int)curr.size() >= K){
if(from != 0)
ans.push_back(from);
}
return curr;
}
void initLCA(){
for(int d = 1; d < MAXD; d++){
for(int i = 1; i <= N; i++){
LCA[i][d] = LCA[LCA[i][d - 1]][d - 1];
}
}
}
int getLCA(int a, int b){
if(depth[a] < depth[b])
swap(a, b);
for(int d = MAXD - 1; d >= 0; d--){
if(depth[a] - (1 << d) >= depth[b]){
a = LCA[a][d];
}
}
for(int d = MAXD - 1; d >= 0; d--){
if(LCA[a][d] != LCA[b][d]){
a = LCA[a][d];
b = LCA[b][d];
}
}
if(a != b)
a = LCA[a][0];
return a;
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> M >> K;
for(int i = 1; i < N; i++){
int a, b;
cin >> a >> b;
adj[b].push_back(make_pair(a, i));
adj[a].push_back(make_pair(b, i));
}
dfs(1, 0);
initLCA();
for(int i = 0; i < M; i++){
int s;
cin >> s;
vector<int> nums(s);
int lca = -1;
for(int i = 0; i < s; i++){
cin >> nums[i];
if(lca == -1){
lca = nums[i];
}
else{
lca = getLCA(lca, nums[i]);
}
}
for(int x: nums){
add[x].push_back(i);
}
sub[lca].push_back(i);
}
dfs2(1, 0, 0);
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for(int x: ans){
cout << x << " ";
}
}
