//
// Created by adavy on 2/11/2023.
//
#include <bits/stdc++.h>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
using ll = long long;
using ld = long double;
using db = double;
using str = string; // yay python!
using ii = pair<int,int>;
using pl = pair<ll,ll>;
using pd = pair<db,db>;
using vi = vector<int>;
using vb = vector<bool>;
using vl = vector<ll>;
using vd = vector<db>;
using vs = vector<str>;
using vii = vector<ii>;
using vpl = vector<pl>;
using vpd = vector<pd>;
#define tcT template<class T
#define tcTU tcT, class U
tcT> using V = vector<T>;
tcT, size_t SZ> using AR = array<T,SZ>;
tcT> using PR = pair<T,T>;
// pairs
#define mp make_pair
#define f first
#define s second
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define len(x) int((x).size())
#define bg(x) begin(x)
#define all(x) bg(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define sor(x) sort(all(x))
#define rsz resize
#define ins insert
#define ft front()
#define bk back()
#define pb push_back
#define eb emplace_back
#define pf push_front
const int MOD = 1e9+7; // 998244353;
const int MX = 1e5+5;
const int LG = 23;
const ll INF = 1e18; // not too close to LLONG_MAX
const ld PI = acos((ld)-1);
const int dx[4] = {1,0,-1,0}, dy[4] = {0,1,0,-1}; // for every grid problem!!
int n, m, k, T=0;
int par[MX][LG]; // node, depth
int dep[MX], euler[MX];
vector<vi> adj(MX);
set<ii> paths;
vector<ii> pairs;
ll val[MX];
void dfs(int nd, int p=-1){
euler[nd] = T++;
par[nd][0] = p;
if (nd!=0) dep[nd] = dep[p]+1;
trav(v, adj[nd]){
if(v != p){
dfs(v, nd);
}
}
}
int lca(int a, int b){
if (dep[a] < dep[b]) swap(a, b);
int ddif = dep[a] - dep[b];
F0R(j, LG) if ((1<<j)&ddif) a = par[a][j];
if (a==b) return a;
R0F(j, LG) if (par[a][j] != par[b][j]) {
a = par[a][j];
b = par[b][j];
}
return par[a][0];
}
void dfs2(int nd, int p=-1){
trav(v, adj[nd]){
if(v != p){
dfs2(v, nd);
if (val[v] >= 2*k){
paths.insert({nd, v});
}
val[nd] += val[v];
}
}
}
int main(){
std::ios::sync_with_stdio(false); cin.tie(NULL);
cin >> n >> m >> k;
memset(val, 0, sizeof(val));
F0R(_, n-1){
int a, b; cin >> a >> b;
a--; b--;
pairs.pb({a,b});
adj[a].pb(b);
adj[b].pb(a);
}
dep[0] = 0;
dfs(0);
//cout << "________________" << endl;
for(int j=1; j<LG;++j) F0R(i, n) par[i][j] = par[par[i][j-1]][j-1];
F0R(_, m){
int num; cin >> num;
vi vals;
F0R(i, num){
int x; cin >> x; x--;
vals.pb(x);
}
sort(all(vals), [](int a, int b){return euler[a]<euler[b];});
vals.pb(vals[0]);
F0R(i, num){
int a = vals[i], b = vals[i+1];
int l = lca(a,b);
val[a]++; val[b]++;
val[l] -= 2;
}
}
//F0R(i, n) cout << val[i] << " ";
//cout << endl;
dfs2(0);
//cout << paths.size() << endl;
vi ans;
F0R(i, n-1){
int a = pairs[i].f, b = pairs[i].s;
if (paths.count({a,b}) || paths.count({b,a})) ans.pb(i+1);
}
cout << ans.size() << endl;
trav(i, ans) cout << i << " ";
cout << endl;
}
