#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define FOR(i, a, b) for (int i = a; i <= b; i++)
#define FORD(i, a, b) for (int i = b; i >= a; i --)
#define REP(i, n) for (int i = 0; i < n; ++i)
#define REPD(i, n) for (int i = n - 1; i >= 0; --i)
#define MASK(i) (1LL << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
constexpr ll LINF = (1ll << 60);
constexpr int INF = (1ll << 30);
constexpr int Mod = 1e9 + 7;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void setupIO(){
#define name "Whisper"
//Phu Trong from Nguyen Tat Thanh High School for gifted student
srand(time(NULL));
cin.tie(nullptr)->sync_with_stdio(false); cout.tie(nullptr);
//freopen(name".inp", "r", stdin);
//freopen(name".out", "w", stdout);
cout << fixed << setprecision(10);
}
template <class X, class Y>
bool minimize(X &x, const Y &y){
X eps = 1e-9;
if (x > y + eps) {x = y; return 1;}
return 0;
}
template <class X, class Y>
bool maximize(X &x, const Y &y){
X eps = 1e-9;
if (x + eps < y) {x = y; return 1;}
return 0;
}
const int MAX = 5e5 + 5;
int numNode, numQuery, numNeed;
vector<pair<int, int>> G[MAX];
unordered_map<int, int> cnt[MAX];
vector<int> ans;
int n[MAX];
void dfs(int u, int p, int edgeId){
for (pair<int, int>&x : G[u]){
int v = x.first, id = x.second;
if(v ^ p){
dfs(v, u, id);
if ((int)cnt[u].size() < (int)cnt[v].size()) swap(cnt[u], cnt[v]);
for (auto&[x, c] : cnt[v]){
cnt[u][x] += c;
if (cnt[u][x] == n[x]) cnt[u].erase(x);
}
}
}
if (cnt[u].size() >= numNeed)
ans.push_back(edgeId);
}
void Whisper(){
cin >> numNode >> numQuery >> numNeed;
for(int i = 1; i < numNode; ++i){
int u, v; cin >> u >> v;
G[u].emplace_back(v, i);
G[v].emplace_back(u, i);
}
for (int i = 1; i <= numQuery; ++i){
cin >> n[i];
for (int v = 1; v <= n[i]; ++v){
int x; cin >> x;
cnt[x][i]++;
}
}
dfs(1, 0, 0);
cout << ans.size() << '\n';
sort(ans.begin(), ans.end());
for (int&v : ans) cout << v << ' ';
}
signed main(){
setupIO();
int Test = 1;
// cin >> Test;
for ( int i = 1 ; i <= Test ; i++ ){
Whisper();
if (i < Test) cout << '\n';
}
}
