#include <bits/stdc++.h>
#define F first
#define S second
using namespace std;
const int MAXN = 1e5 + 105;
typedef pair <int, int> ii;
int log2(int n)
{
return 32 - (int) __builtin_clz(n) - 1;
}
int n, m, k;
int u, v;
vector <ii> g[MAXN + 5];
int in[MAXN + 5], out[MAXN + 5], depth[MAXN + 5], Dad[MAXN + 5][20];
void DFS(int u, int pre)
{
in[u] = ++out[0];
for (ii E : g[u])
{
int v = E.S;
if (v == pre) continue;
depth[v] = depth[u] + 1;
Dad[v][0] = u;
DFS(v, u);
}
out[u] = out[0];
}
void initDad(int n)
{
int N = log2(n);
for (int j = 1; j <= N; ++j)
for (int i = 1; i <= n; ++i)
Dad[i][j] = Dad[Dad[i][j - 1]][j - 1];
}
bool upper(int v, int u)
{
return (in[u] <= in[v] && out[v] <= out[u]);
}
int LCA(int u, int v)
{
if (depth[u] > depth[v]) swap(u, v);
if (upper(v, u)) return u;
for (int i = log2(depth[u]); i >= 0; --i)
{
int Daddy = Dad[u][i];
if (!upper(v, Daddy)) u = Daddy;
}
return Dad[u][0];
}
int cnt[MAXN + 5];
vector <ii> a;
stack <int> st;
vector <int> res;
void DFS_calc(int u, int pre)
{
for (ii E : g[u])
{
int id = E.F;
int v = E.S;
if (v == pre) continue;
DFS_calc(v, u);
if (cnt[v] >= k) res.push_back(id);
cnt[u] += cnt[v];
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i <= n - 1; ++i)
{
cin >> u >> v;
g[u].push_back(ii(i, v));
g[v].push_back(ii(i, u));
}
DFS(1, 1);
initDad(n);
while (m --)
{
int x;
cin >> x;
for (int i = 1; i <= x; ++i)
{
cin >> u;
a.push_back(ii(in[u], u));
}
sort(a.begin(), a.end());
int curLCA = a[0].S;
for (int i = 1; i < x; ++i)
{
int u = a[i - 1].S, v = a[i].S;
int lca = LCA(u, v);
++ cnt[v];
-- cnt[lca];
if (upper(curLCA, lca))
{
++ cnt[curLCA];
-- cnt[lca];
curLCA = lca;
}
}
a.clear();
}
DFS_calc(1, 1);
if (res.size() > 0) sort(res.begin(), res.end());
cout << res.size() << "\n";
for (int id : res) cout << id << " ";
return 0;
}
