#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+5, L = 20;
int n, m, k, tim, dep[N], sz[N], pre[N], pos[N], upId[N], up[L][N];
vector<pair<int, int>> adj[N];
vector<int> End[N];
set<int> st[N];
void dfs(int u, int par, int id, int d) {
pre[u] = tim;
pos[tim] = u;
tim++;
dep[u] = d;
sz[u] = 1;
upId[u] = id;
up[0][u] = par;
for (auto& [v, idx] : adj[u]) {
if (v == par) continue;
dfs(v, u, idx, d + 1);
sz[u] += sz[v];
}
}
int lca(int x, int y) {
if (dep[x] < dep[y]) swap(x, y);
int dif = dep[x] - dep[y];
for (int b = 0; b < L; b++) {
if (dif & (1 << b))
x = up[b][x];
}
if (x == y) return x;
for (int b = L - 1; b >= 0; b--) {
if (up[b][x] == up[b][y]) continue;
x = up[b][x];
y = up[b][y];
}
return up[0][x];
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int x, y;
cin >> x >> y;
x--;
y--;
adj[x].push_back(make_pair(y, i));
adj[y].push_back(make_pair(x, i));
}
tim = 0;
dfs(0, 0, -1, 0);
for (int j = 1; j < L; j++) {
for (int i = 0; i < n; i++) {
up[j][i] = up[j - 1][up[j - 1][i]];
}
}
while (m--) {
int x;
cin >> x;
vector<int> v(x), ord(x);
for (int i = 0; i < x; i++) {
cin >> v[i];
v[i]--;
ord[i] = pre[v[i]];
}
sort(ord.begin(), ord.end());
for (int i = 0; i < x; i++) {
int y = v[i];
auto l = upper_bound(ord.begin(), ord.end(), pre[y]);
if (l != ord.end() && *l < pre[y] + sz[y]) continue;
st[y].insert(m);
}
int l = pos[ord[0]];
int r = pos[ord.back()];
End[lca(l, r)].push_back(m);
}
vector<pair<int, int>> ord(n);
for (int i = 0; i < n; i++) {
ord[i] = make_pair(dep[i], i);
}
sort(ord.rbegin(), ord.rend());
vector<int> ans;
for (int i = 0; i < n; i++) {
int x = ord[i].second;
for (int& y : End[x]) st[x].erase(y);
if (st[x].size() >= k) ans.push_back(upId[x]);
int p = up[0][x];
if (st[x].size() > st[p].size()) swap(st[x], st[p]);
for (int y : st[x]) st[p].insert(x);
st[x].clear();
}
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (int &i : ans) {
cout << i + 1 << " ";
}
cout << "\n";
}
