#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
vector<pair<int, int>> g[100005];
vector<int> res;
int k, c[100005], pp[100005][20], d[100005], dd[100005], a[200005], z = 1;
void dfs(int x, int p) {
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 dfs2(int x, int p, int y) {
for (auto w : g[x]) {
if (w.first == p) continue;
c[x] += dfs2(w.first, x, w.second);
}
if (c[x] >= k * 2 && y != 0) {
res.push_back(y);
}
return c[x];
}
int lca(int x, int y) {
int k = 19;
if (d[x] < d[y]) swap(x, y);
while (k >= 0 && d[x] > d[y]) {
if (d[pp[x][k]] >= d[y]) {
x = pp[x][k];
}
k--;
}
if (x == y) return x;
for (int i = 19; i >= 0; i--) {
if (pp[x][i] != pp[y][i]) {
x = pp[x][i];
y = pp[y][i];
}
}
return pp[x][0];
}
bool cmp(int aa, int bb) {
return dd[aa] < dd[bb];
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, m;
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, -1);
for (int i = 1; i <= m; i++) {
int n;
cin >> n;
for (int i = 0; i < n; i++) {
cin >> a[i];
}
sort(a, a + n, cmp);
a[n] = a[0];
for (int i = 0; i < n; i++) {
int x = a[i], y = a[i + 1], z = lca(x, y);
c[x]++;
c[y]++;
c[z] -= 2;
}
}
dfs2(1, -1, 0);
cout << res.size() << '\n';
sort(res.begin(), res.end());
for (int w : res) {
cout << w << " ";
}
}
