#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#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;
typedef tree<int, null_type, less<int>, rb_tree_tag,tree_order_statistics_node_update> ordered_set;
const int lim = 1e5 + 5;
vector<int> edges[lim];
bool vis[lim];
int ord[lim], num[lim], par[17][lim], dp[lim], depth[lim];
int t;
void dfs(int nd) {
vis[nd] = 1;
ord[nd] = ++t;
num[ord[nd]] = nd;
for(int i = 1; i < 17; ++i)
par[i][nd] = par[i - 1][par[i - 1][nd]];
depth[nd] = max(depth[nd], 1);
for(auto i : edges[nd]) {
if(!vis[i]) {
depth[i] = depth[nd] + 1;
par[0][i] = nd;
dfs(i);
}
}
}
void dfs2(int nd) {
vis[nd] = 1;
for(auto i : edges[nd])
if(!vis[i]) {
dfs2(i);
dp[nd] += dp[i];
}
}
int lca(int u, int v) {
if(depth[u] < depth[v])
swap(u, v);
for(int i = 16; i >= 0; --i) {
if(depth[par[i][u]] >= depth[v])
u = par[i][u];
}
// cerr << u << " " << v << endl;
if(u == v)
return u;
// cerr << "ERROR " << u << " " << v << endl;
for(int i = 16; i >= 0; --i) {
if(par[i][u] != par[i][v])
u = par[i][u], v = par[i][v];
}
return par[0][u];
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(NULL);
int n, m, k;
cin >> n >> m >> k;
map<pair<int, int>, int> arr;
for(int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
edges[u].pb(v);
edges[v].pb(u);
arr[mp(u, v)] = i;
arr[mp(v, u)] = i;
}
dfs(1);
// sort node by ett, then just -1 at lca of both nodes
// -1 at total lca at the end
for(int i = 1; i <= m; ++i) {
int x;
cin >> x;
vector<int> nodes;
while(x--) {
int y;
cin >> y;
nodes.pb(y);
}
for(auto &x : nodes)
x = ord[x];
sort(nodes.begin(), nodes.end());
for(auto &x: nodes)
x = num[x];
// for(auto x : nodes)
// cerr << x << " ";
// cerr << endl;
int total_lca = nodes[0];
for(auto x : nodes)
total_lca = lca(total_lca, x), ++dp[x];
--dp[total_lca];
for(int i = 1; i < nodes.size(); ++i) {
// cerr << nodes[i - 1] << " " << nodes[i] << " " << lca(nodes[i - 1], nodes[i]) << endl;
--dp[lca(nodes[i - 1], nodes[i])];
}
}
memset(vis, 0, sizeof(vis));
dfs2(1);
vector<int> ans;
for(int i = 1; i <= n; ++i) {
// cerr << i << " " << dp[i] << endl;
if(dp[i] >= k) {
ans.pb(arr[mp(i, par[0][i])]);
}
}
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
for(auto x : ans)
cout << x << " ";
cout << endl;
return 0;
}
