#include <bits/stdc++.h>
#define long long long
using namespace std;
/*
啊哈！
想到结论了就很简单了，按照 DFS 序排序，然后直接做就可以了。
这个结论和 寻宝游戏 使用的结论一样。
*/
const int N = (int) 1E5;
const int K = 17;
int n;
int p[K][N], d[N];
int t[N], l[N], c;
vector<pair<int, int>> e[N];
void DFS(int u) {
l[u] = c;
c = c + 1;
for (auto [v, i] : e[u]) {
if (v != p[0][u]) {
p[0][v] = u;
d[v] = d[u] + 1;
t[v] = i;
DFS(v);
}
}
}
int LCA(int u, int v) {
if (d[u] > d[v]) {
swap(u, v);
}
for (int i = K - 1; i >= 0; i--) {
if ((d[v] - d[u]) >> i & 1) {
v = p[i][v];
}
}
if (u == v) {
return u;
}
for (int i = K - 1; i >= 0; i--) {
if (p[i][u] != p[i][v]) {
u = p[i][u];
v = p[i][v];
}
}
return p[0][u];
}
int f[N];
void add(int u, int v) {
f[u] = f[u] + 1;
f[v] = f[v] + 1;
int w = LCA(u, v);
f[w] = f[w] - 2;
}
bool compare(int u, int v) {
return l[u] < l[v];
}
vector<int> answer;
int m, k;
void DFS2(int u) {
for (auto [v, i] : e[u]) {
if (v != p[0][u]) {
DFS2(v);
f[u] = f[u] + f[v];
}
}
if (f[u] >= k * 2) {
answer.push_back(t[u]);
}
}
void solve() {
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int u, v;
cin >> u >> v;
u = u - 1, v = v - 1;
e[u].push_back({v, i});
e[v].push_back({u, i});
}
p[0][0] = -1;
DFS(0);
for (int i = 0; i < K - 1; i++) {
for (int u = 0; u < n; u++) {
if (p[i][u] >= 0) {
p[i + 1][u] = p[i][p[i][u]];
} else {
p[i + 1][u] = -1;
}
}
}
for (int i = 0; i < m; i++) {
int N;
cin >> N;
vector<int> a(N);
for (auto& x : a) {
cin >> x;
x = x - 1;
}
sort(a.begin(), a.end(), compare);
for (int j = 0; j < N; j++) {
add(a[j], a[(j + 1) % N]);
}
}
DFS2(0);
sort(answer.begin(), answer.end());
cout << answer.size() << "\n";
for (auto x : answer) {
cout << x + 1 << " ";
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t;
t = 1;
for (int i = 0; i < t; i++) {
solve();
}
return 0;
}
