/* Author : Mychecksdead */
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
#define oset tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define debug(x) cerr << #x << " is " << x << '\n';
const int N = 1e6+100, M = 1e5+10, F = 2147483646, K = 20;
int n, m, k, dep[N], co[N], up[N][K], timer = 0, in[N], out[N], cur = 0;
vector<pair<int, int>> g[N];
bitset<10005> marked, markede;
vector<pair<int, int>> path;
vector<int> pathe, query[N], qq(N);
bool comp(int &a, int &b){
return dep[a] < dep[b];
}
void dfs(int v, int p){
for(auto u: g[v]){
if(u.first != p){
if(marked[u.first]){
// cout << v << ' ' << u.first << '\n';
int s = path.size() - 1;
while(s >= 0 && !markede[path[s].second]){
co[path[s].second]++;
marked[path[s].first] = 1;
markede[path[s].second] = 1;
// cout << path[s].second << "g\n";
s--;
}
}
path.pb(u);
if(!markede[u.second])
dfs(u.first, v);
if(marked[u.first] && !markede[u.second]){
markede[u.second] = 1, co[u.second]++;
// cout << u.first << ' ' << u.second << "f\n";
}
path.pop_back();
}
}
}
void pre(int v, int p){
dep[v] = dep[p] + 1;
in[v] = timer++;
up[v][0] = p;
for(auto u: g[v]){
if(u.first != p){
pathe.pb(u.second);
pre(u.first, v);
}
}
out[v] = timer++;
}
bool is_ancestor(int u, int v){
return in[u] <= in[v] && out[v] <= out[u];
}
int lca(int u, int v){
if(is_ancestor(u, v)) return u;
if(is_ancestor(v, u)) return v;
for(int j = K - 1; j >= 0; --j){
if(!is_ancestor(up[u][j], v)) u = up[u][j];
}
return up[u][0];
}
void dfs2(int v, int p){
for(auto u: g[v]){
if(u.first != p){
co[u.second] = cur;
dfs2(u.first, v);
}
}
cur += query[v].size();
for(int x: query[v]) qq[x]++;
cur -= qq[v];
}
void solve(){
cin >> n >> m >> k;
for(int i = 0; i < n - 1; ++i){
int u, v; cin >> u >> v;
g[u].pb({v, i});
g[v].pb({u, i});
co[i] = 0;
}
bool ok = 1;
for(int i = 1; i <= n; ++i) if(g[i].size() > 2) ok = 0;
if(ok){
for(int i = 1; i <= n; ++i){
if(g[i].size() == 1){
dep[i] = 0;
pre(i, i);
break;
}
}
vector<pair<int, int>> a;
for(int i = 0; i < m; ++i){
int c; cin >> c;
int l = -1, r = -1;
for(int j = 0; j < c; ++j){
int x; cin >> x;
if(l==-1||dep[x]<dep[l]) l=x;
if(r==-1||dep[x]>dep[r]) r=x;
}
if(l != r)
a.pb({dep[l], dep[r] - 1});
}
sort(all(a));
multiset<int> se;
int p = 0;
for(int i = 1; i < n; ++i){
while(p < a.size() && a[p].first == i) se.insert(a[p].second), p++;
co[pathe[i - 1]] = se.size();
se.erase(i);
}
vector<int> ans;
for(int i = 0; i < n - 1; ++i) if(co[i] >= k) ans.pb(i + 1);
cout << ans.size() << '\n';
for(int p: ans) cout << p << ' ';
return;
}
if(k == m && n > 10000){
dep[1] = 0;
pre(1, 1);
for(int j = 1; j < K; ++j)
for(int i = 1; i <= n; ++i)
up[i][j] = up[up[i][j - 1]][j - 1];
for(int i = 0; i < m; ++i){
int c, l, r; cin >> c;
cin >> l >> r;
int lc = lca(l, r);
query[l].pb(lc), query[r].pb(lc);
}
dfs2(1, 0);
vector<int> ans;
for(int i = 0; i < n - 1; ++i) if(co[i] >= k) ans.pb(i + 1);
cout << ans.size() << '\n';
for(int p: ans) cout << p << ' ';
return;
}
dep[1] = 0;
pre(1, 1);
for(int i = 0; i < m; ++i){
marked = markede = 0;
int c; cin >> c;
vector<int> v;
for(int j = 0; j < c; ++j){
int x; cin >> x;
v.pb(x);
marked[x] = 1;
}
for(int p: v) {path.pb({p, n}); dfs(p, p); path.pop_back();}
// cout << '\n';
}
vector<int> ans;
for(int i = 0; i < n - 1; ++i) if(co[i] >= k) ans.pb(i + 1);
cout << ans.size() << '\n';
for(int p: ans) cout << p << ' ';
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int T = 1, aa;
// cin >> T;aa=T;
while(T--){
// cout << "Case #" << aa-T << ": ";
solve();
cout << '\n';
}
return 0;
}
