#include <bits/stdc++.h>
// #define int long long
using namespace std;
const int mx = 1e5+5;
int n, m, k;
vector<pair<int, int>> g[mx];
int pid[mx];
int pr[20][mx];
int dfn[mx];
int dep[mx];
int a[mx];
int sz;
void dfs(int x, int p) {
dfn[x] = ++sz;
dep[x] = dep[p]+1;
pr[0][x] = p;
for (auto [v, id]:g[x]) {
if (v == p) continue;
pid[v] = id;
dfs(v, x);
}
}
bool cmp(int x, int y) {
return dfn[x] < dfn[y];
}
int lca(int x, int y) {
if (dep[x] > dep[y]) swap(x, y);
int d = dep[y] - dep[x];
for (int i=19;~i;i--) {
if (d & (1<<i)) y = pr[i][y];
}
if (x == y) return x;
for (int i=19;~i;i--) {
if (pr[i][x] != pr[i][y]) {
x = pr[i][x];
y = pr[i][y];
}
}
return pr[0][x];
}
vector<int> ans;
void dfs2(int x, int p) {
for (auto [i, id]:g[x]) {
if (i == p) continue;
dfs2(i, x);
a[x] += a[i];
}
if (a[x] >= 2*k) {
ans.push_back(pid[x]);
}
}
signed main() {
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, 0);
for (int i=1;i<20;i++) {
for (int j=1;j<=n;j++) {
pr[i][j] = pr[i-1][pr[i-1][j]];
}
}
// for (int i=1;i<=n;i++) {
// cout << dfn[i] << " ";
// }
// cout << "owo\n";
for (int i=1;i<=m;i++) {
int x;
cin >> x;
vector<int> ve;
for (int j=1;j<=x;j++) {
int y;
cin >> y;
ve.push_back(y);
}
sort(ve.begin(), ve.end(), cmp);
ve.push_back(ve[0]);
for (int i=0;i+1<ve.size();i++) {
a[ve[i]]++;
a[ve[i+1]]++;
a[lca(ve[i], ve[i+1])]-=2;
}
}
dfs2(1, 0);
cout << ans.size() << "\n";
sort(ans.begin(), ans.end());
for (int i:ans) {
cout << i << " ";
}
cout << "\n";
}
