// ?
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pll;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define debug(x) cerr << #x << ": " << x << endl;
const ll MAXN = 1e5 + 10;
const ll LOG = 20;
int ans[MAXN], n, m, k, par[MAXN][LOG], delta[MAXN], F[MAXN], H[MAXN], tout[MAXN], T; // tin
vector<pll> adj[MAXN];
void dfs(int v, int p) {
H[v] = H[p] + 1;
par[v][0] = p;
for (pll e : adj[v])
if (e.X != p)
dfs(e.X, v);
tout[v] = T++;
}
inline int Par(int v, int k) {
for (int i = LOG - 1; i >= 0; i--)
if (k & (1 << i))
v = par[v][i];
return v;
}
inline int LCA(int v, int u) {
if (H[v] < H[u]) swap(v, u);
v = Par(v, H[v] - H[u]);
if (v == u) return v;
for (int i = LOG - 1; i >= 0; i--)
if (par[v][i] != par[u][i])
v = par[v][i], u = par[u][i];
return par[v][0];
}
void dfs2(int v, int p, int ind) {
F[v] += delta[v];
for (pll e : adj[v]) {
if (e.X != p) {
dfs2(e.X, v, e.Y);
F[v] += F[e.X];
}
}
ans[ind] = F[v] / 2;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++) {
int v, u;
cin >> v >> u;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
dfs(1, 0);
for (int i = 1; i < LOG; i++)
for (int v = 1; v <= n; v++)
par[v][i] = par[par[v][i - 1]][i - 1];
for (int i = 1; i <= m; i++) {
int s;
cin >> s;
vector<int> vec;
for (int i = 1; i <= s; i++) {
int v;
cin >> v;
vec.push_back(v);
}
sort(all(vec), [] (int v, int u) {
return tout[v] < tout[u];
});
for (int i = 0; i < s; i++) {
int v = vec[i], u = vec[(i + 1) % s], lca = LCA(u, v);
delta[v]++;
delta[u]++;
delta[lca] -= 2;
}
}
dfs2(1, 0, 0);
vector<int> vec;
for (int i = 1; i < n; i++)
if (ans[i] >= k)
vec.push_back(i);
cout << vec.size() << endl;
for (int e : vec) cout << e << sep;
cout << endl;
return 0;
}
