#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10;
const int MAXK = 21;
array<int, MAXN> prof, paiEdge, tin, Marc;
array<array<int, MAXK>, MAXN> dp;
array<vector<pair<int, int>>, MAXN> grafo;
vector<int> resp;
int N, M, K;
int temp = 0;
void dfs(int v, int p, int edge)
{
tin[v] = ++temp;
prof[v] = prof[p]+1; paiEdge[v] = edge;
dp[v][0] = p;
for (int k = 1; k < MAXK; k++) dp[v][k] = dp[dp[v][k-1]][k-1];
for (auto [viz, e] : grafo[v])
{
if (viz == p) continue;
dfs(viz, v, e);
}
}
int lca(int a, int b)
{
if (prof[a] < prof[b]) swap(a, b);
int jump = prof[a] - prof[b];
for (int k = 0; k < MAXK; k++) if (jump & (1 << k)) a = dp[a][k];
if (a == b) return a;
for (int k = MAXK-1; k >= 0; k--)
if (dp[a][k] != dp[b][k]) a = dp[a][k], b = dp[b][k];
return dp[a][0];
}
void calcResp(int v, int p)
{
// cerr << v << " " << Marc[v] << " " << paiEdge[v] << '\n';
for (auto [viz, e] : grafo[v])
{
if (viz == p) continue;
calcResp(viz, v);
Marc[v] += Marc[viz];
}
// cerr << v << " " << Marc[v] << " " << paiEdge[v] << '\n';
if (Marc[v] >= 2*K && paiEdge[v] > 0) resp.push_back(paiEdge[v]);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> N >> M >> K;
for (int i = 1; i < N; i++)
{
int X, Y;
cin >> X >> Y;
grafo[X].emplace_back(Y, i);
grafo[Y].emplace_back(X, i);
}
dfs(1, 1, 0);
for (int i = 1; i <= M; i++)
{
int S;
cin >> S;
vector<int> verts(S);
for (auto &x : verts) cin >> x;
sort(verts.begin(), verts.end(), [&](const int &a, const int &b) {return tin[a] < tin[b];});
verts.push_back(verts[0]);
for (int i = 0; i < S; i++)
{
// cerr << verts[i] << " " << verts[i+1] << " " << lca(verts[i], verts[i+1]) << '\n';
Marc[verts[i]]++; Marc[verts[i+1]]++;
Marc[lca(verts[i], verts[i+1])] -= 2;
}
}
calcResp(1, 1);
sort(resp.begin(), resp.end());
cout << resp.size() << '\n';
for (auto x : resp) cout << x << " ";
cout << '\n';
}
