#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define all(v) begin(v), end(v)
using ll = long long;
struct edge {
int to, id;
edge(int to_, int id_) : to(to_), id(id_) {}
};
using Graph = vector<vector<edge>>;
class LowestCommonAncestor {
int n, h;
Graph G;
vector<vector<int>> par;
vector<int> ord, dep;
int cnt = 0;
void dfs(int v, int p) {
par[0][v] = p;
ord[v] = cnt++;
for (auto e : G[v]) {
if (e.to == p) continue;
dep[e.to] = dep[v] + 1;
dfs(e.to, v);
}
}
public:
LowestCommonAncestor(Graph G_) : G(G_) {
n = G.size();
h = 1;
while ((1 << h) < n) ++h;
++h;
par.assign(h, vector<int>(n, -1));
ord.resize(n);
dep.resize(n); dep[0] = 0;
cnt = 0;
dfs(0, -1);
rep (i, h - 1) rep (j, n) par[i + 1][j] = par[i][j] == -1 ? -1 : par[i][par[i][j]];
}
int lca(int a, int b) {
if (dep[a] < dep[b]) swap(a, b);
rrep (i, h) {
if ((dep[a] - dep[b]) >> i & 1) a = par[i][a];
}
if (a == b) return a;
rrep (i, h) {
if (par[i][a] != par[i][b]) {
a = par[i][a];
b = par[i][b];
}
}
return par[0][a];
}
int get_ord(int v) const { return ord[v]; }
};
int main() {
int n, m, k; cin >> n >> m >> k;
Graph g(n);
rep (i, n - 1) {
int a, b; cin >> a >> b;
g[--a].emplace_back(--b, i);
g[b].emplace_back(a, i);
}
LowestCommonAncestor lca(g);
vector<int> imos(n);
rep (i, m) {
int s; cin >> s;
vector<int> v(s);
rep (j, s) cin >> v[j], --v[j];
sort(all(v), [&](int a, int b) { return lca.get_ord(a) < lca.get_ord(b); });
rep (j, s) {
int a = v[j], b = v[(j + 1) % s];
int c = lca.lca(a, b);
++imos[a]; ++imos[b];
imos[c] -= 2;
}
}
vector<int> ans;
auto dfs = [&](auto&& self, int v, int p) -> void {
for (auto e : g[v]) {
if (e.to == p) continue;
self(self, e.to, v);
if (imos[e.to] >= k * 2) ans.push_back(e.id + 1);
imos[v] += imos[e.to];
}
};
dfs(dfs, 0, -1);
sort(all(ans));
cout << ans.size() << endl;
rep (i, ans.size()) {
cout << ans[i];
if (i != ans.size() - 1) cout << " ";
}
cout << endl;
}
