// 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], val[100001], parent[100001][20], start[100001], order[100001];
int cur;
vector<int> adjList[100001], special[100001];
vector<int> edges;
map<pair<int, int>, int> tracks;
void setdepth(int node, int last)
{
order[node] = cur++;
depth[node] = depth[last] + 1;
parent[node][0] = last;
for (int u : adjList[node])
if (u != last)
setdepth(u, node);
}
int lca(int a, int b)
{
for (int i = 19; i >= 0; i--)
{
if (depth[a] - depth[b] >= (1 << i))
a = parent[a][i];
if (depth[b] - depth[a] >= (1 << i))
b = parent[b][i];
}
if (a == b)
return a;
for (int i = 19; i >= 0; i--)
{
if (parent[a][i] != parent[b][i])
{
a = parent[a][i];
b = parent[b][i];
}
}
return parent[a][0];
}
int dfs(int node, int last)
{
int sum = val[node];
for (int u : adjList[node])
if (u != last)
sum += dfs(u, node);
if (sum / 2 >= k)
{
edges.push_back(tracks[{min(node, last), max(node, last)}]);
}
return sum;
}
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;
deque<int> specials;
for (int j = 0; j < s; j++)
{
int a;
cin >> a;
specials.push_back(a);
special[a].push_back(i);
}
sort(all(specials), [](int a, int b)
{ return order[a] < order[b]; });
int ofall = specials[0];
for (int i = 1; i < specials.size(); i++)
ofall = lca(ofall, specials[i]);
specials.push_front(ofall);
for (int i = 0; i < specials.size(); i++)
{
int l = lca(specials[i], specials[(i + 1) % specials.size()]);
val[l] -= 2;
++val[specials[i]];
++val[specials[(i + 1) % specials.size()]];
}
}
dfs(1, 0);
cout << edges.size() << "\n";
sort(all(edges));
for (int u : edges)
cout << u << " ";
cout << "\n";
return 0;
}
