//Oh? You're Approaching Me?
#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
// #pragma GCC optimize("O3,unroll-loops")
#define migmig ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pb push_back
#define F first
#define S second
#define SZ(x) ll((x).size())
#define all(x) (x).begin(), (x).end()
#define cl clear
#define endl '\n'
#define deb(x) cerr << #x << " = " << x << '\n'
#define dokme(x) {cout << x << endl; return;}
#define wtf cout << "[ahaaaaaaaaaaaaaaaa]" << endl;
const int maxn = 2e5 + 21;
const int mod = 998244353;
const int inf = 1e18;
const int LOG = 23;
const int sq = 300;
//g++ main.cpp -o main && main.exe
//#define lc (id * 2)
//#define rc (lc + 1)
//#define mid ((l + r) / 2)
int n, m, k, st[maxn], fn[maxn], ps[maxn], par[maxn][LOG], h[maxn], timer = 0;
vector<pii> G[maxn];
void pre_dfs(int v, int p) {
st[v] = timer++;
par[v][0] = p;
for (int i = 1; i < LOG; i++)
par[v][i] = par[par[v][i - 1]][i - 1];
for (auto [u, i]: G[v]) {
if (u != p) {
h[u] = h[v] + 1;
pre_dfs(u, v);
}
}
fn[v] = timer + 1;
}
int get_par(int v, int d) {
int res = v;
for (int i = 0; i < LOG; i++) {
if ((d >> i) & 1)
res = par[res][i];
}
return res;
}
int LCA(int v, int u) {
if (h[v] > h[u])
swap(v, u);
u = get_par(u, h[u] - h[v]);
if (v == u)
return v;
for (int i = LOG - 1; i >= 0; i--) {
if (par[v][i] != par[u][i]) {
v = par[v][i];
u = par[u][i];
}
}
return par[v][0];
}
void update(int v, int u) {
ps[v]++;
ps[u]++;
ps[LCA(v, u)] -= 2;
return;
}
vector<int> ret;
void dfs(int v, int p, int id = 0) {
for (auto [u, i] : G[v]) {
if (u != p) {
dfs(u, v, i);
ps[v] += ps[u];
}
}
if (id && ps[v] >= k) {
ret.pb(id);
}
}
signed main() {
migmig;
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int v, u;
cin >> v >> u;
G[v].pb({u, i});
G[u].pb({v, i});
}
pre_dfs(1, 0);
for (int i = 1; i <= m; i++) {
int s; cin >> s;
vector<pii> vc;
for (int i = 1; i <= s; i++) {
int x; cin >> x;
vc.pb({st[x], x});
}
sort(all(vc));
for (int i = 0; i < s - 1; i++) {
update(vc[i].S, vc[i + 1].S);
}
}
dfs(1, 0);
cout << SZ(ret) << '\n';
for (int x : ret) {
cout << x << ' ';
}
cout << '\n';
}
