#include<bits/stdc++.h>
using namespace std;
void DBG() { cerr << "]\n"; }
template<class H, class... T> void DBG(H h, T... t) {
cerr << h; if(sizeof...(t)) cerr << ", ";
DBG(t...);
}
#ifdef LOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 0
#endif // LOCAL
#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 each(e,a) for(auto &e : (a))
#define sz(v) (int)(v).size()
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pb push_back
#define tcT template<class T
#define nl "\n"
using ll = long long;
using vi = vector<int>;
using pi = pair<int,int>;
using str = string;
tcT> using V = vector<T>;
tcT> using pqg = priority_queue<T,vector<T>,greater<T>>;
void setIO(string NAME = "") {
cin.tie(0)->sync_with_stdio(0);
if(sz(NAME)) {
freopen((NAME + ".inp").c_str(),"r",stdin);
freopen((NAME + ".out").c_str(),"w",stdout);
}
}
tcT> bool ckmin(T&a, const T&b) {
return b < a ? a=b,1 : 0; }
tcT> bool ckmax(T&a, const T&b) {
return b > a ? a=b,1 : 0; }
const int MOD = 1e9 + 7;
struct BIT {
int N;
vi bit;
void init(int _N) {
N = _N;
bit.assign(N+7, 0);
}
void upd(int p, int val) {
for(; p<=N; p+=p&-p) bit[p] += val;
}
int query(int l, int r) {
int res = 0;
for(; r>0; r -= r&-r) res += bit[r];
for(--l; l>0; l -= l&-l) res -= bit[l];
return res;
}
} fen;
const int MX = 1e5+5, LG = 19;
int N, M, K, tin[MX], tout[MX], dep[MX], par[MX][LG], tt, edgeID[MX];
V<pi> adj[MX];
void dfs(int u, int p) {
tin[u] = ++tt;
each(ed, adj[u]) if(ed.first != p) {
int v = ed.first;
dep[v] = dep[par[v][0] = u] + 1;
edgeID[v] = ed.second;
dfs(v, u);
}
tout[u] = tt;
}
int get_lca(int a, int b) {
if(dep[a] < dep[b]) swap(a,b);
int d = dep[a] - dep[b];
R0F(i,LG) if(d>>i&1) a = par[a][i];
if(a == b) return a;
R0F(i,LG) if(par[a][i] != par[b][i]) {
a = par[a][i];
b = par[b][i];
}
return par[a][0];
}
bool cmp(const int &a, const int &b) {
return tin[a] < tin[b];
}
void solve() {
cin>>N>>M>>K;
fen.init(N+5);
F0R(i,N-1) {
int u,v;
cin>>u>>v;
adj[u].pb({v, i+1});
adj[v].pb({u, i+1});
}
par[1][0] = 1;
dep[1] = 0;
dfs(1, -1);
FOR(j,1,LG) FOR(i,1,N+1) par[i][j] = par[par[i][j-1]][j-1];
F0R(_, M) {
int amt; cin>>amt;
vi lst;
F0R(i, amt) {
int v; cin>>v;
lst.pb(v);
}
sort(all(lst), cmp);
F0R(i,sz(lst)) {
int nxt = (i+1)%sz(lst);
fen.upd(tin[lst[i]], 1);
fen.upd(tin[lst[nxt]], 1);
fen.upd(tin[get_lca(lst[i], lst[nxt])], -2);
}
}
vi ans;
FOR(i,2,N+1) if(fen.query(tin[i], tout[i]) >= 2*K) {
ans.pb(edgeID[i]);
}
sort(all(ans));
cout << sz(ans) << nl;
each(v, ans) cout << v << " ";
cout << nl;
}
int main() {
setIO();
int t=1;
//cin>>t;
while(t-->0) {
solve();
}
return 0;
}
