#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) begin(a),end(a)
using ll = long long;
using vi = vector<int>;
using ar2 = array<int,2>;
using ar3 = array<int,3>;
const int mxN = (int)2e5+10;
const int INF = (int)1e9+1;
const ll LINF = (ll)2e18+1;
const int MOD = (int)1e9+7;
const int mxLg = 20;
int N, M, K;
vector<ar2> adj[mxN];
template<int SZ>
struct Fenwick{
int fen[SZ];
void init(){
memset(fen,0,sizeof(fen));
}
void upd(int x, int v){
for(x++; x<SZ; x+=x&-x)
fen[x]+=v;
}
int sum(int x){
int s = 0;
for(x++; x>0; x-=x&-x)
s+=fen[x];
return s;
}
};
Fenwick<mxN> fen;
int st[mxN], en[mxN];
int jmp[mxLg][mxN];
int edg[mxN];
bool isAnc(int a, int b){
return st[a]<=st[b] and en[a]>=en[b];
}
int lca(int a, int b){
if(isAnc(a,b)) return a;
if(isAnc(b,a)) return b;
for(int i = mxLg-1; i>=0; i--)
if(jmp[i][a] and !isAnc(jmp[i][a],b))
a = jmp[i][a];
return jmp[0][a];
}
int dfs_tim;
int sub[mxN];
void dfs(int s, int p){
sub[s] = 1;
for(int j = 0; j < sz(adj[s]); j++){
auto [u,w] = adj[s][j];
if(u==p) continue;
dfs(u,s); sub[s]+=sub[u];
if(adj[s][0][0]==p or sub[adj[s][0][0]]<sub[u])
swap(adj[s][0],adj[s][j]);
edg[u]=w;
}
en[s] = dfs_tim;
}
int head[mxN];
void dfsHld(int s, int p, int h){
st[s] = ++dfs_tim;
jmp[0][s] = p;
head[s] = h;
for(auto [u,w] : adj[s]){
if(u==p) continue;
dfsHld(u,s,adj[s][0][0]==u?h:u);
}
en[s] = dfs_tim;
}
void upd(int x, int y, int v){
while(head[y]!=head[x]){
fen.upd(st[head[y]],v);
fen.upd(st[x]+1,-v);
y = jmp[0][head[y]];
}
fen.upd(st[x],v);
fen.upd(st[y]+1,-v);
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(0);
cin >> N >> M >> K; fen.init();
for(int i = 1; i < N; i++){
int a, b; cin >> a >> b;
adj[a].pb({b,i}); adj[b].pb({a,i});
}
dfs(1,0); dfs_tim = 0; dfsHld(1,0,1);
for(int j = 1; j < mxLg; j++)
for(int i = 1; i <= N; i++)
jmp[j][i] = jmp[j-1][jmp[j-1][i]];
while(M--){
int n; cin >> n;
vi v; v.clear();
while(n--){
int x; cin >> x;
v.pb(x);
}
sort(all(v),[&](int a, int b){ return st[a]<st[b]; });
for(int i = 1; i < n; i++) v.pb(lca(v[i-1],v[i]));
sort(all(v),[&](int a, int b){ return st[a]<st[b]; });
v.erase(unique(all(v)),end(v));
for(int i = 1; i < sz(v); i++){
int l = lca(v[i-1],v[i]), x = v[i];
for(int i = mxLg-1; i>=0; i--)
if(jmp[i][x] and !isAnc(jmp[i][x],l))
x = jmp[i][x];
upd(x,v[i],1);
}
}
set<int> S;
for(int i = 2; i <= N; i++){
int xd = fen.sum(st[i]);
if(xd>=K) S.insert(edg[i]);
}
cout << sz(S) << "\n";
for(auto u : S) cout << u << " ";
cout << "\n";
}
