#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using ull = unsigned ll;
#define pb push_back
#define mp make_pair
#define eb emplace_back
#define all(x) (x).begin(),(x).end()
#define x first
#define y second
const int MOD = 1e9 + 7;
//const int MOD = 998244353;
const int dx[] = {0, 0, 1, -1};
const int dy[] = {1, -1, 0, 0};
const char dir[] = {'R', 'L', 'D', 'U'};
int add(int a, int b){ //(a + b) % 1e9 + 7
a += b;
if(a >= MOD){
a -= MOD;
}
return a;
}
int sub(int a, int b){
a -= b;
if(a < 0) a += MOD;
return a;
}
int mult(int a, int b){
return ((ll) a * b) % MOD;
}
void setIO() {
ios_base::sync_with_stdio(0);
cin.tie(0);
// freopen((s+".in").c_str(),"r",stdin);
// freopen((s+".text").c_str(),"w",stdout);
}
const int mxN = 100'000;
const int mxD = 17;
vector<pii> adj[mxN];
int depth[mxN];
int bLift[mxN][mxD];
void dfsInitialize(int v, int p) {
for(auto i: adj[v]) {
if(i.x == p)
continue;
depth[i.x] = depth[v] + 1;
bLift[i.x][0] = v;
dfsInitialize(i.x, v);
}
}
void initialize() {
dfsInitialize(0, -1);
for(int d = 1; d < mxD; d++) {
for(int i = 0; i < mxN; i++) {
bLift[i][d] = bLift[bLift[i][d-1]][d-1];
}
}
}
int LCA(int a, int b) {
if(depth[a] < depth[b]) {
swap(a, b);
}
for(int d = mxD-1; d >= 0; d--) {
if(depth[a] - (1<<d) >= depth[b]) {
a = bLift[a][d];
}
}
for(int d = mxD-1; d >= 0; d--) {
if(bLift[a][d] != bLift[b][d]) {
a = bLift[a][d];
b = bLift[b][d];
}
}
if(a != b) {
a = bLift[a][0];
b = bLift[b][0];
}
return a;
}
set<int> stl[mxN];
vector<int> inds[mxN];
vector<int> rmv[mxN];
int amt[mxN];
pii edges[mxN];
void dfsstl(int v, int p){
for(auto i : adj[v]){
if(i.x == p) continue;
dfsstl(i.x, v);
amt[i.y] = stl[i.x].size();
if(stl[i.x].size() > stl[v].size()){
swap(stl[i.x], stl[v]);
}
for(int j : stl[i.x]){
stl[v].insert(j);
}
stl[i.x].clear();
}
for(int i : inds[v]){
stl[v].insert(i);
}
for(int i : rmv[v]){
stl[v].erase(i);
}
}
int main(){
setIO();
int n, m, k; cin >> n >> m >> k;
for(int i = 0; i < n - 1; ++i){
int a, b; cin >> a >> b; --a; --b;
adj[a].eb(mp(b, i));
adj[b].eb(mp(a, i));
edges[i] = mp(a, b);
}
initialize();
for(int i = 0; i < m; ++i){
int s; cin >> s;
int lca = -1;
for(int j = 0; j < s; ++j){
int node; cin >> node; --node;
if(!j) lca = node;
lca = LCA(lca, node);
inds[node].eb(i);
}
rmv[lca].eb(i);
}
dfsstl(0, -1);
vector<int> ans;
for(int i = 0; i < n - 1; ++i){
if(amt[i] >= k){
ans.eb(i);
}
}
cout << ans.size() << "\n";
for(int i : ans){
cout << i + 1 << " ";
}
cout << "\n";
}
