#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii array<int, 2>
const int LG = 16 + 2, N = 1e5 + 4;
int n, m, k, anc[N][LG], h[N], bc[N], e[N], cnt[N];
vector<int> addSen[N], remSen[N];
vector<pii> g[N];
set<int> sack;
void findAnc(int v = 0, int p = 0) {
if (v != 0) {
for (int i = 1; i < LG; ++i) {
int u = anc[v][i - 1];
if (u != -1) {
anc[v][i] = anc[u][i - 1];
}
}
}
for (auto [u, _] : g[v]) {
if (u != p) {
h[u] = h[v] + 1;
anc[u][0] = v;
findAnc(u, v);
}
}
}
int lca(int v, int u) {
if (v == u) {
return v;
}
if (h[v] < h[u])
swap(v, u);
for (int i = 0; i < LG; ++i) {
if ((1 << i) & (h[v] - h[u])) {
v = anc[v][i];
}
}
if (v == u) {
return v;
}
for (int i = LG - 1; i >= 0; --i) {
int vt = anc[v][i];
int ut = anc[u][i];
if (vt != ut && vt != -1 && ut != -1) {
v = vt;
u = ut;
}
}
return anc[v][0];
}
int preDfs(int v = 0, int p = 0) {
int ret = 1, cur = 0;
for (auto [u, edge] : g[v]) {
if (u != p) {
e[u] = edge;
int res = preDfs(u, v);
ret += res;
if (res > cur) {
cur = res;
bc[v] = u;
}
}
}
return ret;
}
void rem(int v, int p) {
for (int sen : addSen[v]) {
auto it = sack.find(sen);
if (it != sack.end()) {
sack.erase(it);
}
}
for (auto [u, _] : g[v]) {
if (u != p) {
rem(u, v);
}
}
}
void add(int v, int p) {
for (auto [u, _] : g[v]) {
if (u != p) {
add(u, v);
}
}
for (int sen : addSen[v]) {
sack.insert(sen);
}
for (int sen : remSen[v]) {
auto it = sack.find(sen);
if (it != sack.end()) {
sack.erase(it);
}
}
}
void dfs(int v = 0, int p = 0) {
for (auto [u, _] : g[v]) {
if (u != p && u != bc[v]) {
dfs(u, v);
rem(u, v);
}
}
if (bc[v] != -1) {
dfs(bc[v], v);
}
for (auto [u, _] : g[v]) {
if (u != p && u != bc[v]) {
add(u, v);
}
}
for (int sen : addSen[v]) {
sack.insert(sen);
}
for (int sen : remSen[v]) {
auto it = sack.find(sen);
if (it != sack.end()) {
sack.erase(it);
}
}
if (v != 0) {
cnt[e[v]] += sack.size();
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 0; i < n - 1; ++i) {
int v, u;
cin >> v >> u;
--v, --u;
g[v].pb({u, i});
g[u].pb({v, i});
}
memset(anc, -1, sizeof anc);
findAnc();
for (int i = 0; i < m; ++i) {
int sz;
cin >> sz;
int l = -1;
while (sz--) {
int v;
cin >> v;
--v;
if (l == -1) {
l = v;
}
else {
l = lca(l, v);
}
addSen[v].pb(i);
}
remSen[l].pb(i);
}
memset(bc, -1, sizeof bc);
preDfs();
dfs();
vector<int> out;
for (int i = 0; i < n - 1; ++i) {
if (cnt[i] >= k) {
out.pb(i + 1);
}
}
cout << out.size() << '\n';
for (int edge : out) {
cout << edge << ' ';
}
return 0;
}
