#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
#define s second
#define f first
typedef long long ll;
const ll MOD = 998244353;
const ll LOGN = 20;
const ll MAXN = 1e5 + 5;
vector<vector<pair<int,int>>> graph;
vector<int> ans;
int tin[MAXN], tout[MAXN], depth[MAXN], up[LOGN][MAXN];
int T = 0, val[MAXN], k;
void dfs(int node, int parent) {
tin[node] = ++T;
for (auto u : graph[node]) {
if (u.f == parent)
continue;
depth[u.f] = depth[node] + 1;
up[0][u.f] = node;
for (int i = 1; i < LOGN; i++)
up[i][u.f] = up[i-1][up[i-1][u.f]];
dfs(u.f, node);
}
tout[node] = T;
}
int find(int node, int k) {
for (int i = 0; i < LOGN; i++) {
if ((1<<i) & k)
node = up[i][node];
}
return node;
}
int lca(int a, int b) {
if (depth[b] > depth[a])
swap(a, b);
a = find(a, depth[a] - depth[b]);
if (a == b)
return a;
for (int i = LOGN - 1; i >= 0; i--) {
if (up[i][a] != up[i][b]) {
a = up[i][a];
b = up[i][b];
}
}
return up[0][a];
}
int dfs2(int node, int parent_edge) {
for (auto u : graph[node]) {
if (u.s != parent_edge)
val[node] += dfs2(u.f, u.s);
}
if (val[node] >= k && node != 1)
ans.push_back(parent_edge);
return val[node];
}
int main() {
fast
int n, m, a, b;
cin >> n >> m >> k;
graph = vector<vector<pair<int,int>>>(n+1, vector<pair<int,int>>());
for (int i = 1; i < n; i++) {
cin >> a >> b;
graph[a].push_back({b, i});
graph[b].push_back({a, i});
}
for (int i = 0; i < LOGN; i++)
up[i][1] = 1;
dfs(1, 1);
int q, p;
for (int i = 0; i < m; i++) {
cin >> q;
vector<int> all;
for (int j = 0; j < q; j++) {
cin >> p;
all.push_back(p);
val[p]++;
}
sort(all.begin(), all.end(), [&](int a, int b) {
return tin[a] < tin[b];
});
all.push_back(all[0]);
for (int i = 1; i < all.size(); i++) {
int lowest = lca(all[i-1], all[i]);
val[lowest] -= 2;
}
}
dfs2(1, -1);
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (auto u : ans)
cout << u << " ";
cout << "\n";
}
