//I wrote this code 4 u <3
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif
struct HLD {
vector<int> par, siz, head, tin;
vector<vector<int>> g;
int dfs1(int u) {
for (int &to : g[u]) {
if (to == par[u]) {
continue;
}
par[to] = u;
siz[u] += dfs1(to);
if (siz[to] > siz[g[u][0]] || g[u][0] == par[u]) swap(to, g[u][0]);
}
return siz[u];
}
void dfs2(int u, int &timer) {
tin[u] = timer++;
for (int to : g[u]) {
if (to == par[u]) {
continue;
}
head[to] = (timer == tin[u] + 1 ? head[u] : to);
dfs2(to, timer);
}
}
HLD(vector<vector<int>> &g, int r = 0) : par(g.size(), -1), siz(g.size(), 1), head(g.size(), r), tin(g.size()), g(g) {
dfs1(r);
int timer = 0;
dfs2(r, timer);
}
vector<pair<int, int>> path(int a, int b) {
vector<pair<int, int>> res;
for (;; b = par[head[b]]) {
if (tin[b] < tin[a]) swap(a, b);
if (tin[head[b]] <= tin[a]) {
res.emplace_back(tin[a] + 1, tin[b] + 1);
return res;
}
res.emplace_back(tin[head[b]], tin[b] + 1);
}
}
int lca(int a, int b) {
for (;; b = par[head[b]]) {
if (tin[b] < tin[a]) swap(a, b);
if (tin[head[b]] <= tin[a]) return a;
}
}
};
template<typename T>
class Fenwick { //0-indexed, [l, r)
public:
vector<T> t;
int n;
Fenwick() = default;
explicit Fenwick(int n) : t(n + 1), n(n) {}
T get(int x) {
T ans = 0;
for (x; x > 0; x -= x & -x) {
ans += t[x];
}
return ans;
}
T get(int l, int r) {
return get(r) - get(l);
}
void upd(int x, T v) {
for (++x; x <= n; x += x & -x) {
t[x] += v;
}
}
int kth(T k) {
int x = 0;
for (int i = 1 << __lg(n); i > 0; i >>= 1) {
if (x + i <= n && t[x + i] < k) {
k -= t[x += i];
}
}
return x;
}
};
signed main(int32_t argc, char *argv[]) {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> g(n);
vector<pair<int, int>> e;
for (int i = 1; i < n; ++i) {
int u, v;
cin >> u >> v;
--u, --v;
e.emplace_back(u, v);
g[u].push_back(v);
g[v].push_back(u);
}
HLD tr(g);
vector<int> par(n);
for (int i = 0; i < n - 1; ++i) {
auto [u, v] = e[i];
if (tr.tin[u] > tr.tin[v]) swap(u, v);
par[tr.tin[v]] = i;
}
Fenwick<int> bit(n + 1);
for (int i = 0; i < m; ++i) {
int K;
cin >> K;
vector<int> v(K);
for (int j = 0; j < K; ++j) {
cin >> v[j];
--v[j];
}
int lca = v[0];
for (int j = 1; j < K; ++j) {
lca = tr.lca(lca, v[j]);
}
vector<pair<int, int>> ev;
for (auto x : v) {
for (auto [lx, rx] : tr.path(lca, x)) {
if (lx == rx) continue;
ev.emplace_back(lx, -1);
ev.emplace_back(rx, 1);
}
}
sort(ev.begin(), ev.end());
vector<pair<int, int>> add;
int last = 0, c = 0;
for (auto [x, t] : ev) {
if (t == 1 && c == 1) {
bit.upd(last, 1);
bit.upd(x, -1);
}
c -= t;
if (t == -1 && c == 1) {
last = x;
}
}
}
vector<int> ans;
for (int i = 0; i < n; ++i) {
if (bit.get(i + 1) >= k) {
ans.push_back(par[i]);
}
}
cout << ans.size() << '\n';
sort(ans.begin(), ans.end());
for (auto i : ans) {
cout << i + 1 << ' ';
}
}
/*
*/
