#include <bits/stdc++.h>
#define taskname ""
using namespace std;
using ld = long double;
using ull = unsigned long long;
using ll = long long;
using pii = pair <int, int>;
const char el = '\n';
const char sp = ' ';
const int maxN = 2e5 + 10;
const int LOG = 21;
int n, m, k, timer;
int st[maxN], en[maxN], sub[maxN], head[maxN], edge_idx[maxN];
int up[maxN][LOG];
vector <pii> adj[maxN];
int bit[maxN];
void update(int x, int v)
{
for (; x < maxN; x += x & -x) bit[x] += v;
}
int query(int x)
{
int res = 0;
for (; x > 0; x -= x & -x) res += bit[x];
return res;
}
void dfs_sz(int u, int p)
{
sub[u] = 1;
up[u][0] = p;
for (int i = 1; i < LOG; ++i) up[u][i] = up[up[u][i - 1]][i - 1];
for (int i = 0; i < (int)adj[u].size(); ++i)
{
if (adj[u][i].first == p) continue;
dfs_sz(adj[u][i].first, u);
sub[u] += sub[adj[u][i].first];
if (adj[u][0].first == p || sub[adj[u][i].first] > sub[adj[u][0].first])
{
swap(adj[u][0], adj[u][i]);
}
}
}
void dfs_hld(int u, int p, int h, int weight)
{
st[u] = ++timer;
head[u] = h;
edge_idx[u] = weight;
for (int i = 0; i < (int)adj[u].size(); ++i)
{
int v = adj[u][i].first;
int w = adj[u][i].second;
if (v == p) continue;
dfs_hld(v, u, (i == 0 ? h : v), w);
}
en[u] = timer;
}
bool is_anc(int u, int v)
{
return st[u] <= st[v] && en[u] >= en[v];
}
int get_lca(int u, int v)
{
if (is_anc(u, v)) return u;
if (is_anc(v, u)) return v;
for (int i = LOG - 1; i >= 0; --i)
{
if (up[u][i] && !is_anc(up[u][i], v)) u = up[u][i];
}
return up[u][0];
}
void path_upd(int u, int v, int val)
{
while (head[u] != head[v])
{
update(st[head[v]], val);
update(st[v] + 1, -val);
v = up[head[v]][0];
}
update(st[u], val);
update(st[v] + 1, -val);
}
int main ()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
if (fopen(taskname ".inp", "r"))
{
freopen(taskname ".inp", "r", stdin);
freopen(taskname ".out", "w", stdout);
}
if (!(cin >> n >> m >> k)) return 0;
for (int i = 1; i < n; ++i)
{
int u, v;
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
dfs_sz(1, 0);
dfs_hld(1, 0, 1, 0);
while (m--)
{
int num;
cin >> num;
vector <int> v(num);
for (int &x : v) cin >> x;
sort(v.begin(), v.end(), [&](int a, int b) { return st[a] < st[b]; });
for (int i = 1; i < num; ++i) v.push_back(get_lca(v[i - 1], v[i]));
sort(v.begin(), v.end(), [&](int a, int b) { return st[a] < st[b]; });
v.erase(unique(v.begin(), v.end()), v.end());
for (int i = 1; i < (int)v.size(); ++i)
{
int l = get_lca(v[i - 1], v[i]);
int curr = v[i];
for (int j = LOG - 1; j >= 0; --j)
{
if (up[curr][j] && !is_anc(up[curr][j], l)) curr = up[curr][j];
}
path_upd(curr, v[i], 1);
}
}
vector <int> res;
for (int i = 2; i <= n; ++i)
{
if (query(st[i]) >= k) res.push_back(edge_idx[i]);
}
sort(res.begin(), res.end());
cout << res.size() << el;
for (int x : res) cout << x << sp;
cout << el;
return 0;
}
