#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int n, m, k, x;
vector<pair<int, int>> g[100005];
int c[100005], pp[100005][20], d[100005], dd[100005], z = 1;
void dfs(int x, int p = 0) {
d[x] = d[p] + 1;
dd[x] = z++;
pp[x][0] = p;
for (int i = 1; i < 20; i++) {
pp[x][i] = pp[pp[x][i - 1]][i - 1];
}
for (auto w : g[x]) {
if (w.first == p) continue;
dfs(w.first, x);
}
}
int lca(int a, int b) {
int i = 19;
if (d[a] < d[b]) swap(a, b);
while (i >= 0 && d[a] > d[b]) {
if (d[pp[a][i]] >= d[b]) {
a = pp[a][i];
}
i--;
}
if (a == b) return a;
for (int i = 19; i >= 0; i--) {
if (pp[a][i] != pp[b][i]) {
a = pp[a][i];
b = pp[b][i];
}
}
return pp[a][0];
}
vector<int> res;
int dfs2(int x, int p = 0, int y = 0) {
for (auto w : g[x]) {
if (w.first == p) continue;
c[x] += dfs2(w.first, x, w.second);
}
if (c[x] >= k * 2 && y) {
res.push_back(y);
}
return c[x];
}
bool cmp(int aa, int bb) {
return dd[aa] < dd[bb];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
g[u].push_back({v, i});
g[v].push_back({u, i});
}
dfs(1);
for (int i = 1; i <= m; i++) {
cin >> x;
vector<int> v(x);
for (int i = 0; i < x; i++) {
cin >> v[i];
}
sort(v.begin(), v.end(), cmp);
v.push_back(v[0]);
for (int i = 0; i < x; i++) {
int x = v[i], y = v[i + 1], z = lca(x, y);
c[x]++;
c[y]++;
c[z] -= 2;
}
}
dfs2(1);
cout << res.size() << '\n';
sort(res.begin(), res.end());
for (int w : res) {
cout << w << " ";
}
}
