#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
struct BIT{
int n;
vector<ll> sm;
BIT(){}
BIT(int _n){
n = _n;
sm.resize(n);
}
void add(int in, ll x){
in++;
while(in <= n) sm[in-1]+=x, in+=in&-in;
}
void add(int l, int r, ll x){
add(l, x);
if(r+1 < n) add(r+1, -x);
}
ll get(int in){
in++;
ll s = 0;
while(in >= 1) s+=sm[in-1], in-=in&-in;
return s;
}
};
struct HLD{
int n;
vector<vector<int>> v;
vector<int> sz;
vector<int> id;
vector<int> top;
vector<int> depth;
vector<int> p;
vector<int> dfs_array;
int cnt = 0;
BIT bit;
HLD(int _n){
n = _n;
v.assign(n, {});
}
void pre_dfs(int nd, int ss, int d){
for(int x: v[nd]) if(x != ss) pre_dfs(x, nd, d+1);
p[nd] = ss;
depth[nd] = d;
for(int x: v[nd]) if(x != ss) sz[nd]+=sz[x];
}
void dfs(int nd, int ss, int tp){
id[nd] = cnt;
cnt++;
dfs_array.pb(nd);
top[nd] = tp;
int mx = 0, in = -1;
for(int x: v[nd]) if(x != ss && sz[x] > mx) mx = sz[x], in = x;
if(in != -1) dfs(in, nd, tp);
for(int x: v[nd]) if(x != ss && x != in) dfs(x, nd, x);
}
void init(){
sz.assign(n, 1);
p.assign(n, -1);
depth.assign(n, -1);
pre_dfs(0, -1, 0);
id.assign(n, -1);
top.assign(n, -1);
dfs(0, -1, 0);
bit = BIT(n);
}
void upd(vector<int> s){
priority_queue<tuple<int, int, int>> pq;
for(int x: s) pq.push({depth[top[x]], top[x], x});
while(!pq.empty()){
int tp = top[get<2>(pq.top())];
int mx = id[get<2>(pq.top())], mn = id[get<2>(pq.top())];
while(!pq.empty() && get<1>(pq.top()) == tp){
mx = max(mx, id[get<2>(pq.top())]);
mn = min(mn, id[get<2>(pq.top())]);
pq.pop();
}
if(pq.empty()){
if(mn < mx) bit.add(mn+1, mx, 1);
}
else{
bit.add(id[tp], mx, 1);
pq.push({depth[top[p[tp]]], top[p[tp]], p[tp]});
}
}
}
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, m, k; cin >> n >> m >> k;
map<pair<int, int>, int> mp;
HLD hld(n);
for(int i = 1; i < n; i++){
int a, b; cin >> a >> b; a--, b--;
if(a > b) swap(a, b);
mp[{a, b}] = i;
hld.v[a].pb(b);
hld.v[b].pb(a);
}
hld.init();
for(int i = 0; i < m; i++){
int si; cin >> si;
vector<int> s(si);
for(int &x: s) cin >> x, x--;
hld.upd(s);
}
vector<int> ans;
for(int i = 1; i < n; i++){
if(hld.bit.get(i) >= k){
int a = hld.dfs_array[i], b = hld.p[a];
if(a > b) swap(a, b);
ans.pb(mp[{a, b}]);
}
}
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for(int x: ans) cout << x << " ";
cout << "\n";
}
