/*
#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
*/
#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define eb emplace_back
#define PI acos(-1.0)
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define BIT(x, i) (1 & ((x) >> (i)))
#define MASK(x) (1LL << (x))
#define task "tnc"
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
typedef long long ll;
typedef long double ld;
const ll INF = 1e18;
const int maxn = 3e5 + 5;
const int mod = 1e9 + 7;
const int mo = 998244353;
using pi = pair<ll, ll>;
using vi = vector<ll>;
using pii = pair<pair<ll, ll>, ll>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, m, k;
vector<pair<int, int>> G[maxn];
vector<int> G1[maxn];
int id[maxn];
int tin[maxn];
int tout[maxn];
int eu[maxn];
int par[maxn];
pair<int, int> rmq[maxn][19];
int l = 0;
void dfs(int u, int pa)
{
eu[++l] = u;
tin[u] = l;
for (auto v : G[u])
{
if (v.fi == pa)
continue;
par[v.fi] = v.se;
dfs(v.fi, u);
eu[++l] = u;
}
tout[u] = l;
}
void init()
{
for (int i = 1; i <= l; i++)
{
rmq[i][0] = {tin[eu[i]], eu[i]};
}
for (int j = 1; (1 << j) <= l; j++)
{
for (int i = 1; i + (1 << j) - 1 <= l; i++)
{
rmq[i][j] = min(rmq[i][j - 1], rmq[i + (1 << (j - 1))][j - 1]);
}
}
}
int LCA(int u, int v)
{
if (tin[u] > tin[v])
swap(u, v);
int dis = 31 - __builtin_clz(tin[v] - tin[u] + 1);
return min(rmq[tin[u]][dis], rmq[tin[v] - (1 << dis) + 1][dis]).se;
}
int cac[maxn];
void dfs1(int u)
{
for (auto v : G1[u])
{
cac[v] += 1;
cac[u] -= 1;
dfs1(v);
}
}
vector<int> ans;
void dfs2(int u, int pa)
{
for (auto v : G[u])
{
if (v.fi == pa)
continue;
dfs2(v.fi, u);
cac[u] += cac[v.fi];
}
if (cac[u] >= k)
{
ans.pb(par[u]);
}
}
bool cmp(int u, int v)
{
return tin[u] < tin[v];
}
signed main()
{
cin.tie(0), cout.tie(0)->sync_with_stdio(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
G[a].pb({b, i});
G[b].pb({a, i});
}
dfs(1, -1);
init();
for (int i = 1; i <= m; i++)
{
int k;
cin >> k;
vector<int> d;
vector<int> d1;
for (int j = 1; j <= k; j++)
{
int x;
cin >> x;
d.pb(x);
G1[x].clear();
}
sort(d.begin(), d.end(), cmp);
d1 = d;
for (int j = 1; j < d.size(); j++)
{
d1.pb(LCA(d[j], d[j - 1]));
}
sort(d1.begin(), d1.end());
d1.resize(distance(d1.begin(), unique(d1.begin(), d1.end())));
sort(d1.begin(), d1.end(), cmp);
for (auto v : d1)
{
// cout << v << " ";
G1[v].clear();
}
// cout << "\n";
for (int j = 1; j < d1.size(); j++)
{
// cout<<LCA(d1[j],d1[j-1])<<" "<<d1[j]<<"\n";
G1[LCA(d1[j], d1[j - 1])].pb(d1[j]);
}
dfs1(d1[0]);
}
dfs2(1, -1);
cout << ans.size() << "\n";
sort(ans.begin(), ans.end());
for (auto v : ans)
{
cout << v << " ";
}
}
