#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 1 , LOG = 20;
int n , m , k , T = 0;
vector<int> in(N) , out(N) , d(N) , id(N) , ans;
vector<vector<int>> g(N) , w(N) , ins(N) , ers(N) , up(N , vector<int>(LOG));
void dfs(int u , int p = 1){
in[u] = ++T;
d[u] = d[p] + 1;
up[u][0] = p;
for(int x = 0;x < (int)g[u].size();x ++){
if(g[u][x] != p){
dfs(g[u][x] , u);
id[g[u][x]] = w[u][x];
}
}
out[u] = T;
}
int lca(int u , int v){
if(d[u] < d[v]){
swap(u , v);
}
int s = d[u] - d[v];
for(int bit = 0;bit < LOG;bit ++){
if(s >> bit & 1){
u = up[u][bit];
}
}
if(u == v){
return u;
}
for(int bit = LOG - 1;bit >= 0;bit --){
if(up[u][bit] != up[v][bit]){
u = up[u][bit];
v = up[v][bit];
}
}
return up[u][0];
}
multiset<int> DFS(int u , int p = 0){
multiset<int> S;
for(int x : ins[u]){
S.insert(x);
}
for(int x = 0;x < (int)g[u].size();x ++){
if(g[u][x] != p){
auto t = DFS(g[u][x] , u);
if((int)S.size() < (int)t.size()){
swap(S , t);
}
for(int x : t){
S.insert(x);
}
}
}
for(int x : ers[u]){
S.erase(x);
}
set<int> o;
for(int x : S){
o.insert(x);
}
if((int)o.size() >= k && id[u] > 0){
ans.push_back(id[u]);
}
return S;
}
int main(){
cin >> n >> m >> k;
for(int i = 1;i < n;i ++){
int u , v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
w[u].push_back(i);
w[v].push_back(i);
}
dfs(1);
for(int bit = 1;bit < LOG;bit ++){
for(int u = 1;u <= n;u ++){
up[u][bit] = up[up[u][bit - 1]][bit - 1];
}
}
for(int i = 1;i <= m;i ++){
int s;
cin >> s;
vector<int> v(s + 1);
int min_in = n + 1 , max_out = 0;
for(int x = 1;x <= s;x ++){
cin >> v[x];
min_in = min(min_in , in[v[x]]);
max_out = max(max_out , out[v[x]]);
}
for(int x = 1;x <= s;x ++){
int max_lca = v[x];
for(int bit = LOG - 1;bit >= 0;bit --){
if(in[up[max_lca][bit]] > min_in || out[up[max_lca][bit]] < max_out){
max_lca = up[max_lca][bit];
}
}
if(in[max_lca] > min_in || out[max_lca] < max_out){
max_lca = up[max_lca][0];
}
ins[v[x]].push_back(i);
ers[max_lca].push_back(i);
}
}
DFS(1);
cout << (int)ans.size() << endl;
for(int i = 0;i < (int)ans.size();i ++){
cout << ans[i] << " ";
}
cout << endl;
}
