//thatsramen
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define eb emplace_back
#define pb push_back
#define ft first
#define sd second
#define pi pair<int, int>
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define dbg(...) dbg_out(__VA_ARGS__)
using ll = long long;
using ld = long double;
using namespace std;
using namespace __gnu_pbds;
//Constants
const ll INF = 5 * 1e18;
const int IINF = 2 * 1e9;
const ll MOD = 1e9 + 7;
// const ll MOD = 998244353;
const ll dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
const ld PI = 3.14159265359;
//Templates
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) {return os << '(' << p.first << ", " << p.second << ')';}
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) {os << '['; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << ']';}
void dbg_out() {cerr << endl;}
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << H << ' '; dbg_out(T...); }
template<typename T> void mins(T& x, T y) {x = min(x, y);}
template<typename T> void maxs(T& x, T y) {x = max(x, y);}
template<typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T> using omset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>;
//order_of_key(k): number of elements strictly less than k
//find_by_order(k): k-th element in the set
void setPrec() {cout << fixed << setprecision(15);}
void unsyncIO() {cin.tie(0)->sync_with_stdio(0);}
void setIn(string s) {freopen(s.c_str(), "r", stdin);}
void setOut(string s) {freopen(s.c_str(), "w", stdout);}
void setIO(string s = "") {
unsyncIO(); setPrec();
if(s.size()) setIn(s + ".in"), setOut(s + ".out");
}
// #define TEST_CASES
void solve() {
int n, m, k;
cin >> n >> m >> k;
vector<vector<pi>> e(n + 5);
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
e[u].pb({v, i}); e[v].pb({u, i});
}
vector<int> par(n + 5), dep(n + 5, 0);
function<void(int, int)> dfs_init = [&](int f, int p) {
for (const auto &[to, id] : e[f]) {
if (to == p) continue;
dep[to] = dep[f] + 1;
par[to] = f;
dfs_init(to, f);
}
};
dfs_init(1, -1);
par[1] = 1;
vector<vector<int>> jump(n + 5, vector<int> (20));
for (int i = 1; i <= n; i++) {
jump[i][0] = par[i];
}
for (int i = 1; i < 20; i++) {
for (int j = 1; j <= n; j++) {
jump[j][i] = jump[jump[j][i - 1]][i - 1];
}
}
auto get = [&](int u, int v) -> int {
if (dep[u] < dep[v]) swap(u, v);
for (int i = 19; i >= 0; i--) {
int to = jump[u][i];
if (dep[to] >= dep[v]) {
u = to;
}
}
if (u == v) return u;
for (int i = 19; i >= 0; i--) {
if (jump[u][i] != jump[v][i]) {
u = jump[u][i];
v = jump[v][i];
}
}
return par[u];
};
vector<int> val(n + 5, 0);
vector<map<int, int>> comps(n + 5);
for (int i = 0; i < m; i++) {
int z; cin >> z;
vector<int> cur(z);
for (int j = 0; j < z; j++) {
cin >> cur[j];
}
for (int j = 0; j < z - 1; j++) {
int lca = get(cur[j], cur[j + 1]);
comps[cur[j]][i]++;
comps[cur[j + 1]][i]++;
comps[lca][i] -= 2;
}
}
vector<int> sz(n + 5), ans;
function<void(int, int)> dfs_size = [&](int f, int p) {
sz[f] = (int) comps[f].size();
for (const auto &[to, id] : e[f]) {
if (to == p) continue;
dfs_size(to, f);
sz[f] += sz[to];
}
};
dfs_size(1, -1);
auto merge = [&](int u, int v) {
for (const auto &[x, y] : comps[v]) {
comps[u][x] += y;
if (comps[u][x] == 0) {
comps[u].erase(x);
}
}
};
function<void(int, int)> dfs = [&](int f, int p) {
int big = -1, big_id = -1;
for (const auto &[to, id] : e[f]) {
if (to == p) continue;
if (big == -1 || sz[to] > sz[big])
big = to, big_id = id;
}
if (big != -1) {
dfs(big, f);
if ((int) comps[big].size() >= k)
ans.pb(big_id + 1);
swap(comps[big], comps[f]);
merge(f, big);
}
for (const auto &[to, id] : e[f]) {
if (to == p || to == big) continue;
dfs(to, f);
if ((int) comps[to].size() >= k)
ans.pb(id + 1);
merge(f, to);
}
//dbg(f, comps[f]);
};
dfs(1, -1);
cout << ans.size() << '\n';
sort(all(ans));
for (int x : ans) {
cout << x << ' ';
}
}
int main() {
setIO();
int tt = 1;
#ifdef TEST_CASES
cin >> tt;
#endif
while (tt--)
solve();
return 0;
}
