// header file
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
// pragma
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
// macros
#define endl "\n"
#define ll long long
#define mp make_pair
#define ins insert
#define lb lower_bound
#define pb push_back
#define ub upper_bound
#define lll __int128
#define fi first
#define se second
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_multiset;
const int lim = 1e5 + 5;
int dep_cnt[lim];
struct disjoint_set {
int head[lim], size[lim], ans[lim];
map<int, int> dep[lim];
disjoint_set() {
memset(head, -1, sizeof(head));
fill(size, size + lim, 1);
memset(ans, 0, sizeof(ans));
}
int fh(int nd) {
while(head[nd] != -1)
nd = head[nd];
return nd;
}
bool merge(int x, int y) {
x = fh(x), y = fh(y);
if(x != y) {
if(size[x] < size[y])
swap(x, y);
size[x] += size[y], head[y] = x;
for(auto i : dep[y]) {
if(dep[x][i.fi]) {
dep[x][i.fi] += i.se;
if(dep[x][i.fi] == dep_cnt[i.fi])
--ans[x];
}
else {
dep[x][i.fi] += i.se;
if(dep[x][i.fi] != dep_cnt[i.fi])
++ans[x];
}
}
}
return x != y;
}
};
vector<int> edges[lim], dep_nd[lim], ans;
bool vis[lim];
int k, depth[lim];
disjoint_set dsu;
void dfs(int nd) {
vis[nd] = 1;
for(auto i : dep_nd[nd]) {
++dsu.dep[nd][i];
if(dep_cnt[i] != 1)
++dsu.ans[nd];
}
for(auto i : edges[nd]) {
if(!vis[i])
depth[i] = depth[nd] + 1, dfs(i), dsu.merge(nd, i);
}
//cout << "ND " << nd << " " << dsu.ans[dsu.fh(nd)] << endl;
if(dsu.ans[dsu.fh(nd)] >= k)
ans.pb(nd);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(NULL);
// have a tree, find which edges should be constructed
// constructed edges -> use lca, using LCA, we can find what edges should be connected
// LCA of adj edges
// sol 2:
// use subtree count
// in each node, a par edge is used if not all the neighborhoods are in the subtree
// use DSU On Tree, maintaining count of elements and amount of active
// ez
int n, m;
cin >> n >> m >> k;
vector<pair<int, int>> adj;
for(int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
edges[u].pb(v);
edges[v].pb(u);
adj.pb(mp(u, v));
}
for(int i = 1; i <= m; ++i) {
int s;
cin >> s;
dep_cnt[i] = s;
while(s--) {
int x;
cin >> x;
dep_nd[x].pb(i);
}
}
dfs(1);
// yang child di fi
// se jadi number
for(int i = 0; i < adj.size(); ++i) {
if(depth[adj[i].fi] < depth[adj[i].se])
swap(adj[i].fi, adj[i].se);
adj[i].se = i + 1;
}
sort(adj.begin(), adj.end());
vector<int> res;
for(auto i : ans)
res.pb((*lower_bound(adj.begin(), adj.end(), mp(i, 0))).se);
//cout << endl;
sort(res.begin(), res.end());
cout << res.size() << endl;
for(auto i : res)
cout << i << " ";
cout << endl;
return 0;
}
