#include <bits/stdc++.h>
#define int long long
using namespace std;
vector<vector<int>> g, p;
vector<int> d, add, ans, tin;
int tim;
void dfs(int no, int rt, int dis) {
if(rt != -1) p[no][0] = rt;
d[no] = dis;
tin[no] = tim;
tim++;
for(auto i: g[no]) {
if(i == rt) continue;
dfs(i, no, dis+1);
}
}
int lca(int u, int v) {
if(d[u] > d[v]) swap(u, v);
int k = d[v]-d[u];
for(int i=0; i<=30; i++) {
if(k & (1 << i)) v = p[v][i];
}
if(u == v) return u;
for(int i=30; i>=0; i--) {
if(p[u][i] != p[v][i]) {
u = p[u][i];
v = p[v][i];
}
}
return p[u][0];
}
void dfs2(int no, int rt) {
ans[no] += add[no];
for(auto i: g[no]) {
if(i == rt) continue;
dfs2(i, no);
ans[no] += ans[i];
}
}
void update(int u, int v) {
u = p[u][0];
v = p[u][0];
add[lca(u, v)]--;
add[p[lca(u, v)][0]]--;
add[u]++;
add[v]++;
}
signed main() {
cin.tie(0)->sync_with_stdio(0);
int n, m, k;
cin >> n >> m >> k;
g.assign(n+2, vector<int>());
p.assign(n+2, vector<int>(32, 0));
vector<pair<int, int>> edge;
vector<int> ch;
d.assign(n+2, 0); ans.assign(n+2, 0);
add.assign(n+2, 0); edge.assign(n+2, {0, 0});
tin.assign(n+2, 0);
for(int i=1; i<n; i++) {
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
edge[i].first = u;
edge[i].second = v;
}
dfs(1, -1, 0);
for(int i=1; i<=30; i++) {
for(int j=1; j<=n; j++) {
p[j][i] = p[p[j][i-1]][i-1];
}
}
while(m--) {
int s;
cin >> s;
vector<pair<int, int>> node;
while(s--) {
int u;
cin >> u;
node.push_back({tin[u], u});
}
sort(node.begin(), node.end());
node.push_back(node.front());
for(int i=0; i<node.size()-1; i++) {
update(node[i].second, node[i+1].second);
}
}
add[1] += add[0];
dfs2(1, -1);
for(int i=1; i<=n; i++) {
int u = edge[i].first, v = edge[i].second;
if(d[u] > d[v]) swap(u, v);
if(ans[u] >= 2*k) ch.push_back(i);
}
cout << ch.size() << "\n";
for(auto i: ch) cout << i << " ";
}
