#include<bits/stdc++.h>
#define fi first
#define se second
#define int long long
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using aa = array<int,3>;
const int N = 1e5+5;
const ll INF = 1e18;
const int MOD = 1e9+7;
int n, q, k, u, v, timer = 0;
// RMQ
int st[18][2 * N];
// euler tour
int tin[N], tout[N], b[2 * N], id[2 * N];
// tree
vector<ii> adj[N];
// queries
int a[N * 2], pre[N];
vector <int> res;
bool inside(int u,int v){
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
bool cmp(int a,int b){
return tin[a] < tin[b];
}
void dfs(int u,int p){
tin[u] = ++timer;
b[timer] = tin[u];
id[timer] = u;
for (ii it : adj[u]){
if (it.fi == p) continue;
dfs(it.fi,u);
b[++timer] = tin[u];
}
tout[u] = timer;
}
void precompute_RMQ(){
for (int i = 1; i <= timer; i++) st[0][i] = b[i];
for (int j = 1; j <= 17; j++){
for (int i = 1; i + (1 << j) - 1 <= timer; i++){
st[j][i] = min(st[j - 1][i],st[j - 1][i + (1 << (j - 1))]);
}
}
}
int LCA(int u,int v){
int l = tin[u];
int r = tin[v];
if (l > r) swap(l,r);
int k = __lg(r - l + 1);
return id[min(st[k][l],st[k][r - (1 << k) + 1])];
}
void solve(){
cin >> k;
for (int i = 1; i <= k; i++) cin >> a[i];
sort(a+1,a+1+k,cmp);
for (int i = 1; i < k; i++){
a[i + k] = LCA(a[i],a[i + 1]);
}
k = 2 * k - 1;
sort(a+1,a+1+k,cmp);
k = unique(a+1,a+1+k) - a - 1;
stack<int> st;
st.push(a[1]);
for (int i = 1; i <= k; i++){
while (!inside(st.top(),a[i])){
st.pop();
}
pre[a[i]]++;
pre[st.top()]--;
st.push(a[i]);
}
}
void dp(int u,int p){
for (ii it : adj[u]){
if (it.fi == p) continue;
dp(it.fi,u);
if (pre[it.fi] >= k) res.push_back(it.se);
pre[u] += pre[it.fi];
}
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);cout.tie(NULL);
cin >> n >> q >> k;
for (int i = 1; i < n; i++){
cin >> u >> v;
adj[u].push_back({v,i});
adj[v].push_back({u,i});
}
dfs(1,0);
precompute_RMQ();
while (q--){
solve();
}
dp(1,0);
sort(res.begin(),res.end());
res.erase(unique(res.begin(),res.end()),res.end());
cout << (int)res.size() << '\n';
for (int it : res) cout << it << ' ';
return 0;
}
