#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
typedef long long ll;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
typedef vector<vii> vvii;
int n, m, k, markCount[100050], newInds[100050], pSum[100050], returnInd[100050];
vvii adj;
vii edges;
bitset<100050> visited, isDest;
void dfs(int u, int ind) {
//cerr << "// dfs(" << u << ", " << ind << ")\n";
if (newInds[u] != -1) return;
newInds[u] = ind;
returnInd[ind] = u;
for (ii edge : adj[u]) dfs(edge.fi, ind + 1);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
adj.assign(n + 20, vii());
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
edges.push_back({a, b});
adj[a].push_back({b, i});
adj[b].push_back({a, i});
}
int globalStart = 0;
for (int i = 0; i < n; i++) {
if (adj[i].size() == 1) globalStart = i;
}
//globalStart = 1;
memset(newInds, -1, sizeof newInds);
dfs(globalStart, 0);
//for (int i = 0; i < n; i++) cerr << "// " << i << " became " << newInds[i] << '\n';
for (int j = 0; j < m; j++) {
int s;
cin >> s;
int minS = 1e9, maxS = 0;
for (int i = 0; i < s; i++) {
int tmp; cin >> tmp;
minS = min(minS, newInds[tmp]);
maxS = max(maxS, newInds[tmp]);
}
//cerr << "// minS : " << minS << '\n';
//cerr << "// maxS : " << maxS << '\n';
pSum[minS]++;
pSum[maxS + 1]--;
}
for (int i = 1; i < 100050; i++) pSum[i] += pSum[i - 1];
//for (int i = 0; i < n; i++) cerr << "// pSum[" << i << "] : " << pSum[i] << '\n';
vi ans;
for (int i = 0; i < n - 1; i++) {
if (pSum[i] >= k) ans.push_back(returnInd[i]);
}
cout << (int)ans.size() << '\n';
for (int i = 0; i < (int)ans.size(); i++) {
if (i) cout << ' ';
cout << ans[i] + 1;
}
cout << '\n';
}
