// Codeforces Handle : thaonguyendethuongvai
// FB : Nuoc Khoang
#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")
#define endl "\n"
#define tn int
#define pair pair< tn, tn >
#define fi first
#define se second
#define thaonguyen( i, a, b ) for( tn i = a; i <= b; i++ )
#define nguyenthao( i, a, b ) for( tn i = b; i >= a; i-- )
#define thaonguyenxinh ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
const tn N = 1e5 + 5;
const tn M = __lg(2*N) + 2;
pair railway[N];
map< pair, tn > mp;
vector<tn> g[N], vertex, result;
vector<tn> euler;
tn high[N], pos[N], minHigh[2 * N][20];
tn n, q, k, u, v, z;
tn cnt[N], dp[N], valid[N], pp[N];
void dfs(int u, int par) {
pos[u] = euler.size();
euler.push_back(u);
for (int v : g[u]) {
if (v == par) continue;
high[v] = high[u] + 1;
pp[v] = u;
dfs(v, u);
euler.push_back(u);
}
}
tn MIN_HIGH(tn x, tn y) {
return high[x] < high[y] ? x : y;
}
void buildLCA() {
tn sz = euler.size();
for (tn i = 0; i < sz; i++) minHigh[i][0] = euler[i];
for (tn j = 1; (1 << j) <= sz; j++)
for (tn i = 0; i + (1 << j) <= sz; i++)
minHigh[i][j] = MIN_HIGH(minHigh[i][j - 1], minHigh[i + (1 << (j - 1))][j - 1]);
}
tn lca(tn u, tn v) {
tn pu = pos[u], pv = pos[v];
if (pu > pv) swap(pu, pv);
tn k = 31 - __builtin_clz(pv - pu + 1);
return MIN_HIGH(minHigh[pu][k], minHigh[pv - (1 << k) + 1][k]);
}
bool cmp(tn a, tn b){
return pos[a] < pos[b];
}
void floyd(tn u, tn par){
dp[u] = valid[u];
for(tn v : g[u]){
if(v == par) continue;
floyd(v, u);
dp[u] += dp[v];
}
}
void dijkstra(tn u, tn par){
dp[u] = 0;
valid[u] = 0;
for(tn v : g[u]){
if(v == par || !dp[v]) continue;
cnt[v]++;
dijkstra(v, u);
}
}
signed main(){
thaonguyenxinh;
cin >> n >> q >> k;
thaonguyen(i, 1, n - 1){
cin >> u >> v;
if(u > v) swap(u, v);
mp[{u, v}] = i;
g[u].push_back(v);
g[v].push_back(u);
}
dfs(1, -1);
buildLCA();
thaonguyen(j, 1, q){
cin >> z;
vertex.clear();
if(z == 1) continue;
thaonguyen(i, 1, z){
cin >> u;
valid[u] = 1;
vertex.push_back(u);
}
sort(vertex.begin(), vertex.end(), cmp);
thaonguyen(i, 0, z - 2)
vertex.push_back(lca(vertex[i], vertex[i+1]));
sort(vertex.begin(), vertex.end(), cmp);
vertex.erase(unique(vertex.begin(), vertex.end()), vertex.end());
floyd(vertex[0], -1);
dijkstra(vertex[0], -1);
}
thaonguyen(i, 1, n){
if(cnt[i] >= k){
tn a = i, b = pp[i];
if(a > b) swap(a, b);
result.push_back(mp[{a, b}]);
}
}
sort(result.begin(), result.end());
cout << result.size() << endl;
for(tn v : result) cout << v << " ";
}
