// 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, val[100001], special[100001], depth[100001], finalv[100001];
int startnode, startdepth;
vector<int> adjList[100001];
vector<int> edges;
map<pair<int, int>, int> tracks;
bool dfs(int node, int last)
{
bool out = false;
bool all = true;
int cnt = 0;
for (int u : adjList[node])
if (u != last)
{
++cnt;
bool t = dfs(u, node);
out |= t;
all &= t;
}
if (all || special[node])
{
if (special[node] || cnt > 1)
{
if (depth[node] < startdepth)
{
startnode = node;
startdepth = depth[node];
}
}
}
if (special[node])
out = true;
if (!out)
--val[node];
return out;
}
void setdepth(int node, int last)
{
depth[node] = depth[last] + 1;
for (int u : adjList[node])
if (u != last)
setdepth(u, node);
}
void traverse(int node, int last, int curval)
{
curval += val[node];
finalv[node] = curval;
for (int u : adjList[node])
if (u != last)
traverse(u, node, curval);
}
void recurse(int node, int last)
{
for (int u : adjList[node])
if (u != last)
{
if (min(finalv[u], finalv[node]) >= k)
edges.push_back(tracks[{min(u, node), max(u, node)}]);
recurse(u, node);
}
}
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 = 0; i < m; i++)
{
memset(special, 0, sizeof(special));
int s;
cin >> s;
for (int j = 0; j < s; j++)
{
int a;
cin >> a;
special[a] = 1;
}
startnode = 0;
startdepth = INT_MAX;
dfs(1, 0);
++val[startnode];
}
traverse(1, 0, 0);
recurse(1, 0);
cout << edges.size() << "\n";
sort(all(edges));
for (int u : edges)
cout << u << " ";
cout << "\n";
return 0;
}
