#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 100, lg = 30;
int n ,m ,k, st[maxn], fn[maxn], cnt , par[lg][maxn], h[maxn], dp[maxn];
vector<int> adj[maxn];
map<pair<int, int>, int> mapi;
vector<pair<int, int>> q;
vector<int> ans;
void dfs(int v ,int mpar = 0){
st[v] = cnt++;
par[0][v] = mpar;
for(int i = 1 ; i < lg ; i++){
par[i][v] = par[i - 1][par[i - 1][v]];
}
for(auto u : adj[v]){
if(u != mpar){
h[u] = h[v] + 1;
dfs(u, v);
}
}
fn[v] = cnt++;
}
int lca(int u ,int v){
if(h[v] >= h[u]){
swap(v ,u);
}
for(int i = lg - 1 ;i >= 0 ; i--){
if(h[par[i][u]] >= h[v]){
u = par[i][u];
}
}
if(u == v){
return u;
}
for(int i= lg - 1; i >= 0 ; i--){
if(par[i][u] != par[i][v]){
u = par[i][u] , v = par[i][v];
}
}
return par[0][u];
}
void check(int v ,int mpar = 0){
for(auto u : adj[v]){
if(u != mpar){
check(u, v);
}
}
dp[mpar] += dp[v];
if(dp[v] >= (2 * k) and mapi[{v ,mpar}] != 0){
ans.push_back(mapi[{v ,mpar}]);
}
}
int main(){
ios::sync_with_stdio(0), cout.tie(0), cin.tie(0);
cin >> n >> m >> k;
for(int i = 1 ;i < n; i++){
int x ,y;
cin >> x >> y;
adj[x].push_back(y);
adj[y].push_back(x);
mapi[{x ,y}]= i;
mapi[{y , x}]= i;
}
//h[1] = 1;
dfs(1);
while(m--){
int x;
cin >> x;
q.push_back({0, 0});
for(int i = 1 ; i <= x ; i++){
int y;
cin >> y;
q.push_back({st[y], y});
}
sort(q.begin(), q.end());
for(int i = 2 ; i <= x ; i++){
dp[q[i - 1].second]++;
dp[q[i].second]++;
dp[lca(q[i].second, q[i - 1].second)] -= 2;
}
dp[q[1].second]++;
dp[q[x].second]++;
dp[lca(q[x].second, q[1].second)] -= 2;
q.clear();
}
check(1);
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
for(auto i : ans){
cout << i << ' ';
}
cout << endl;
return 0;
}
