// dmoj problem: https://vjudge.net/contest/765976#problem/G
#include <bits/stdc++.h>
#define int long long
#define all(x) x.begin(), x.end()
using namespace std;
int n, m, k, depth[100001], finalv[100001], parent[100001][20];
int startnode, startdepth;
vector<int> adjList[100001], add[100001], rm[100001];
vector<int> edges, specials;
map<pair<int, int>, int> tracks;
void setdepth(int node, int last)
{
depth[node] = depth[last] + 1;
parent[node][0] = last;
for (int u : adjList[node])
if (u != last)
setdepth(u, node);
}
set<int> recurse(int node, int last)
{
set<int> mayors;
for (int u : add[node])
mayors.insert(u);
for (int u : adjList[node])
{
if (u != last)
{
for (int x : recurse(u, node))
mayors.insert(x);
}
}
finalv[node] = mayors.size();
for (int u : rm[node])
mayors.erase(u);
return mayors;
}
bool allequal(vector<int> &check)
{
bool allequal = true;
for (int i = 1; i < check.size(); i++)
allequal &= check[i] == check[0];
return allequal;
}
int lca(vector<int> &nodes)
{
int targetdepth = INT_MAX;
for (int u : nodes)
targetdepth = min(targetdepth, depth[u]);
for (int i = 19; i >= 0; i--)
for (int j = 0; j < nodes.size(); j++)
if (depth[nodes[j]] - targetdepth >= (1 << i))
nodes[j] = parent[nodes[j]][i];
if (allequal(nodes))
return nodes[0];
for (int i = 19; i >= 0; i--)
{
vector<int> t;
for (int j = 0; j < nodes.size(); j++)
t.push_back(parent[j][i]);
if (!allequal(t))
swap(nodes, t);
}
return parent[nodes[0]][0];
}
int32_t main()
{
cin.sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
adjList[a].push_back(b);
adjList[b].push_back(a);
tracks[{min(a, b), max(a, b)}] = i;
}
setdepth(1, 0);
for (int i = 1; i < 20; i++)
for (int j = 1; j <= n; j++)
parent[j][i] = parent[parent[j][i - 1]][i - 1];
for (int i = 0; i < m; i++)
{
int s;
cin >> s;
specials.clear();
for (int j = 0; j < s; j++)
{
int a;
cin >> a;
specials.push_back(a);
add[a].push_back(i);
}
rm[lca(specials)].push_back(i);
}
recurse(1, 0);
for (int i = 1; i <= n; i++)
{
for (int u : adjList[i])
if (u > i && min(finalv[u], finalv[i]) >= k)
{
edges.push_back(tracks[{min(u, i), max(u, i)}]);
}
}
cout << edges.size() << "\n";
sort(all(edges));
for (int u : edges)
cout << u << " ";
cout << "\n";
return 0;
}
