#include <bits/stdc++.h>
#include <cassert>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
#define MAX 101010
#define MAXS 18
#define INF 10000000000000
#define bb ' '
#define ln '\n'
#define Ln '\n'
set<int> st[MAX];
vector<int> adj[MAX];
int psum[MAX];
pii edges[MAX];
int pedge[MAX];
int sp[MAX][MAXS];
int dep[MAX];
void dfs(int x) {
int i;
for (i = 1; i < MAXS; i++) sp[x][i] = sp[sp[x][i - 1]][i - 1];
for (auto v : adj[x]) if (v != sp[x][0]) {
sp[v][0] = x;
dep[v] = dep[x] + 1;
dfs(v);
}
}
int lca(int u, int v) {
if (!u) return v;
if (!v) return u;
int i;
if (dep[u] != dep[v]) {
if (dep[u] > dep[v]) swap(u, v);
int d = dep[v] - dep[u];
for (i = 0; i < MAXS; i++) if (d >> i & 1) v = sp[v][i];
}
if (u == v) return u;
for (i = MAXS - 1; i >= 0; i--) if (sp[u][i] != sp[v][i]) u = sp[u][i], v = sp[v][i];
return sp[u][0];
}
void calc(int x) {
int sum = st[x].size();
for (auto v : adj[x]) if (v != sp[x][0]) {
calc(v);
sum += st[v].size();
if (st[v].size() > st[x].size()) st[v].swap(st[x]);
for (auto a : st[v]) st[x].insert(a);
}
psum[x] -= (sum - st[x].size());
for (auto v : adj[x]) if (v != sp[x][0]) psum[x] += psum[v];
}
signed main() {
ios::sync_with_stdio(false), cin.tie(0);
int N, M, K;
cin >> N >> M >> K;
int i, a, b;
for (i = 1; i < N; i++) {
cin >> a >> b;
edges[i] = { a, b };
adj[a].push_back(b);
adj[b].push_back(a);
}
dep[1] = 1;
dfs(1);
for (i = 1; i < N; i++) {
tie(a, b) = edges[i];
pedge[(sp[a][0] == b) ? a : b] = i;
}
int v;
for (i = 1; i <= M; i++) {
int s;
cin >> s;
int l = 0;
vector<int> lst;
while (s--) cin >> v, lst.push_back(v);
sort(lst.begin(), lst.end());
lst.erase(unique(lst.begin(), lst.end()), lst.end());
if (lst.size() == 1) {
K--;
continue;
}
for (auto v : lst) {
psum[v]++;
st[v].insert(i);
l = lca(v, l);
}
psum[l]--;
}
calc(1);
vector<int> ansv;
for (i = 1; i <= N; i++) if (psum[i] >= K) ansv.push_back(pedge[i]);
sort(ansv.begin(), ansv.end());
cout << ansv.size() << Ln;
for (auto v : ansv) cout << v << bb;
}
