#include <bits/stdc++.h>
using namespace std;
#define DEBUG(x) //x
#define A(x) DEBUG(assert(x))
#define PRINT(x) DEBUG(cerr << x)
#define PV(x) DEBUG(cerr << #x << " = " << x << '\n')
#define PV2(x) DEBUG(cerr << #x << " = " << x.first << ',' << x.second << '\n')
#define PAR(x) DEBUG(PRINT(#x << " = { "); for (auto y : x) PRINT(y << ' '); PRINT("}\n");)
#define PAR2(x) DEBUG(PRINT(#x << " = { "); for (auto [y, z] : x) PRINT(y << ',' << z << " "); PRINT("}\n");)
typedef long long i64;
const int INF = 1000000007; //998244353;
struct S {
int n, m, k, t;
vector<vector<pair<int, int>>> edges;
vector<vector<int>> anc;
vector<int> dep, ord, pos, subtree, val, in;
constexpr static int LOG = 20;
void run() {
cin >> n >> m >> k;
edges.resize(n);
for (int i = 1; i < n; ++i) {
int a, b;
cin >> a >> b;
--a; --b;
edges[a].push_back({b, i});
edges[b].push_back({a, i});
}
anc.resize(LOG, vector<int>(n, 0));
dep.resize(n, 0); subtree.resize(n, 1);
pos.resize(n, 0); ord.resize(n, 0);
in.resize(n, 0);
t = 0;
dfs(0);
for (int jump = 1; jump < LOG; ++jump) {
for (int i = 0; i < n; ++i) {
anc[jump][i] = anc[jump - 1][anc[jump - 1][i]];
}
}
PAR(in);
val.resize(n, 0);
while (m--) {
int x; cin >> x;
vector<int> nodes(x + 1);
for (int i = 0; i < x; ++i) {
cin >> nodes[i]; --nodes[i];
}
sort(nodes.begin(), nodes.begin() + x, [&](int a, int b) {
return pos[a] < pos[b];
});
nodes[x] = nodes[0];
PAR(nodes);
for (int i = 0; i < x; ++i) {
int lca = LCA(nodes[i], nodes[i + 1]);
++val[nodes[i]];
++val[nodes[i + 1]];
PV(lca);
val[lca] -= 2;
}
PAR(in);
}
PAR(val);
dfs2(0);
vector<int> ans;
PAR(val);
PV(k);
PAR(in);
for (int i = 1; i < n; ++i) {
if (val[i] >= 2 * k) {
ans.push_back(in[i]);
}
}
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (int i = 0; i < ans.size(); ++i) {
cout << ans[i] << (i + 1 == ans.size() ? '\n' : ' ');
}
}
void dfs(int node) {
pos[node] = t;
ord[t++] = node;
for (auto [next, id] : edges[node]) {
if (next != anc[0][node]) {
anc[0][next] = node;
dep[next] = dep[node] + 1;
in[next] = id;
dfs(next);
subtree[node] += subtree[next];
}
}
}
void dfs2(int node) {
for (auto [next, id] : edges[node]) {
if (next != anc[0][node]) {
dfs2(next);
val[node] += val[next];
}
}
}
int kth_anc(int k, int a) {
for (int jump = LOG - 1; jump >= 0; --jump) {
if (1 << jump <= k) {
a = anc[jump][a];
k -= 1 << jump;
}
}
return a;
}
int LCA(int a, int b) {
if (dep[a] < dep[b]) swap(a, b);
a = kth_anc(dep[a] - dep[b], a);
if (a == b) return a;
for (int jump = LOG - 1; jump >= 0; --jump) {
if (anc[jump][a] != anc[jump][b]) {
a = anc[jump][a];
b = anc[jump][b];
}
}
return anc[0][a];
}
};
int main() {
ios::sync_with_stdio(0); cin.tie(0);
auto sol = make_unique<S>();
sol->run();
}
