#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pll pair<long long, long long>
#define pb push_back
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
const ll N = 2e5 + 100;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const ll block = 450;
struct Fen{
ll n;
vector<ll>bit1, bit2;
void init(ll _n){
n = _n;
bit1.resize(_n + 10), bit2.resize(_n + 10);
};
void updatePoint(vector<ll>& b, int u, ll v) {
int idx = u;
while (idx <= n) {
b[idx] = (b[idx] + v);
idx += (idx & (-idx));
}
}
void updateRange(int l, int r, ll v) {
updatePoint(bit1, l, ((n - l + 1) * v));
updatePoint(bit1, r + 1, (-(n - r) * v));
updatePoint(bit2, l, v);
updatePoint(bit2, r + 1, -v);
}
ll getSum(vector<ll>& b, ll u) {
ll idx = u, ans = 0;
while (idx > 0) {
ans = (ans + b[idx]);
idx -= (idx & (-idx));
}
return ans;
}
ll prefixSum(ll u) {
ll x = (getSum(bit1, u) - (getSum(bit2, u) * (n - u)));
return x;
}
ll rangeSum(int l, int r) {
ll x = (prefixSum(r) - prefixSum(l - 1));
return x;
}
} ft;
ll n,m,timer = 0,k;
ll sz[N], heavy[N], tin[N], head[N], p[N];
vector<pll>adj[N];
ll id[N];
void dfs(ll u, ll par){
sz[u] = 1;
for(auto x : adj[u]){
ll v = x.F, i = x.S;
if(v == par) continue;
dfs(v, u);
p[v] = u;
id[v] = i;
sz[u] += sz[v];
if(sz[v] > sz[heavy[u]]) heavy[u] = v;
}
}
void HLD(ll u, ll h){
head[u] = h; tin[u] = ++timer;
if(heavy[u]) HLD(heavy[u], h);
for(auto x : adj[u]){
ll v = x.F;
if(v != p[u] && v != heavy[u]) HLD(v, v);
}
}
ll upd(ll a, ll b){
ll res = 0;
for(; head[a] != head[b]; b = p[head[b]]){
if(tin[a] > tin[b]) swap(a, b);
ft.updateRange(tin[head[b]], tin[b], 1);
}
if(tin[a] > tin[b]) swap(a, b);
ft.updateRange(tin[a], tin[b], 1);
ft.updateRange(tin[a], tin[a], -1);
return res;
}
void to_thic_cau(){
cin >> n >> m >> k;
for(int i = 1; i <= n - 1;i++){
ll u,v; cin >> u >> v;
adj[u].pb({v, i});
adj[v].pb({u, i});
}
dfs(1, 0); HLD(1, 0);
ft.init(n);
for(int i = 1; i <= m;i++){
vector<ll>vec;
ll sz; cin >> sz;
for(int j = 1; j <= sz;j++){
ll x; cin >> x;
vec.pb(x);
}
sort(all(vec), [&](const ll &a, const ll &b){
return tin[a] < tin[b];
});
for(int i = 1; i < vec.size();i++) upd(vec[i-1], vec[i]);
upd(vec[0], vec.back());
}
vector<ll>ans;
for(int i = 2; i <= n;i++){
if(ft.rangeSum(tin[i], tin[i]) >= 2 * k){
ans.pb(id[i]);
}
}
sort(all(ans));
cout << ans.size() << "\n";
for(auto x : ans) cout << x << ' ';
cout << "\n";
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll tc = 1;
//cin >> tc;
while(tc--) to_thic_cau();
}
