#include <bits/stdc++.h>
#define file_io freopen("input.txt", "r", stdin);freopen("output.txt", "w", stdout);
#define fast_io ios::sync_with_stdio(false);cin.tie(0);
#define what(x) cerr << #x << " is " << x << '\n';
#define kill(x) {cout << x << '\n'; return 0;}
#define all(x) (x).begin(), (x).end()
#define pii pair<int, int>
#define pll pair<ll, ll>
#define pb push_back
#define ll long long
#define F first
#define S second
const ll inf = 1e18, mod = 1e9 + 7, delta = 1e9 + 9, SQ = 450, P = 6065621;
using namespace std;
const ll N = 1e5 + 10, LG = 20;
int h[N], par[N][LG], f[N], cnt[N], k;
vector<pii> adj[N];
vector<int> ans;
void pre (int v, int p = -1, int e = -1) {
par[v][0] = p;
f[v] = e;
if (p != -1) h[v] = h[p] + 1;
for (int i = 1; i < LG; i++)
if (par[v][i - 1] != -1)
par[v][i] = par[par[v][i - 1]][i - 1];
for (auto u: adj[v])
if (p != u.F)
pre(u.F, v, u.S);
}
int lca (int u, int v) {
if (h[u] < h[v]) swap(u, v);
for (int i = LG - 1; i >= 0; i--)
if (par[u][i] != -1 && h[par[u][i]] >= h[v])
u = par[u][i];
if (u == v) return u;
for (int i = LG - 1; i >= 0; i--)
if (par[u][i] != par[v][i])
u = par[u][i], v = par[v][i];
return par[u][0];
}
void dfs (int v, int p = -1) {
for (auto u: adj[v]) {
if (u.F != p) {
dfs(u.F, v);
if (cnt[u.F] >= k) {
ans.pb(u.S);
}
cnt[v] += cnt[u.F];
cnt[u.F] = 0;
}
}
}
int main() {
fast_io;
int n, m;
cin >> n >> m >> k;
memset(par, -1, sizeof par);
for (int i = 1; i < n; i++) {
int u, v;
cin >> u >> v;
adj[u].pb({v, i});
adj[v].pb({u, i});
}
pre(1);
for (int i = 1; i <= m; i++) {
int x;
cin >> x;
vector<int> d(x);
for (int j = 0; j < x; j++)
cin >> d[j];
int l = lca(d[0], d[1]);
cnt[l]--;
for (int j = 2; j < x; j++)
l = lca(l, d[j]), cnt[l]--;
// cnt[l]++;
for (auto u: d)
cnt[u]++;
cnt[l] -= x;
}
dfs(1);
cout << ans.size() << '\n';
sort(all(ans));
for (auto u: ans) cout << u << ' ';
cout << '\n';
return 0;
}
