#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
int n, m, k;
vector<int> adj[maxn];
int timer;
int val[maxn];
int tin[maxn], up[maxn][20], depth[maxn];
pair<int, int> edges[maxn];
int id[maxn];
vector<int> ans;
void dfs(int u, int p)
{
tin[u] = ++timer;
for (auto v : adj[u])
{
if (v == p) continue;
depth[v] = depth[u] + 1;
up[v][0] = u;
for (int i = 1; i < 20; ++i) up[v][i] = up[up[v][i-1]][i-1];
dfs(v, u);
}
}
int lca(int u, int v)
{
if (depth[u] < depth[v]) swap(u, v);
int k = depth[u] - depth[v];
for (int i = 0; i < 20; ++i) if (k >> i & 1) u = up[u][i];
if (u == v) return u;
for (int i = 19; i >= 0; --i)
{
if (up[u][i] != up[v][i])
{
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
void dfs2(int u, int p)
{
for (auto v : adj[u])
{
if (v == p) continue;
dfs2(v, u);
val[u] += val[v];
}
if (u != 1 && val[u] / 2 >= k) ans.push_back(id[u]);
}
int main()
{
ios::sync_with_stdio(false); cin.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; ++i)
{
int u, v; cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
edges[i] = {u, v};
}
dfs(1, 0);
for (int i = 1; i < n; ++i)
{
int u = edges[i].first;
int v = edges[i].second;
if (depth[u] < depth[v]) swap(u, v);
id[u] = i;
}
for (int i = 1; i <= m; ++i)
{
int s; cin >> s;
vector<int> nd(s);
for (int j = 0; j < s; ++j) cin >> nd[j];
sort(nd.begin(), nd.end(), [&](int u, int v){return tin[u] < tin[v];});
for (int j = 0; j < s; ++j)
{
int u = nd[j];
int v = nd[(j+1)%s];
val[u]++;
val[v]++;
val[lca(u, v)] -= 2;
}
}
dfs2(1, 0);
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (auto i : ans) cout << i << ' ';
return 0;
}
