#include <bits/stdc++.h>
// #define endl '\n'
#define all(x) x.begin(),x.end()
#define sz(x) ((int)x.size())
#define x first
#define y second
#define pb push_back
#define ppb pop_back
#define pf push_front
#define ppf pop_front
#define ll long long
#define ld long double
#define ii pair<int, int>
#define iii pair<int, ii>
#define vi vector<int>
using namespace std;
const int ms = 2e5+100;
const int mlg = 23;
const int sigma = 30;
int n, m, k, t, posorder = 0;
vi g[ms];
set<int> nec;
set<int> res;
map<ii, int> id;
map<int, int> h;
int pres[ms];
int order[ms];
int par[ms][mlg+1], lvl[ms];
void dfs(int v, int p, int l = 0) { // chamar como dfs(root, root)
lvl[v] = l;
par[v][0] = p;
order[v] = posorder++;
for(int k = 1; k <= mlg; k++) {
par[v][k] = par[par[v][k-1]][k-1];
}
for(int u : g[v]) {
if(u != p) dfs(u, v, l + 1);
}
}
int lca(int a, int b) {
if(lvl[b] > lvl[a]) swap(a, b);
for(int i = mlg; i >= 0; i--) {
if(lvl[a] - (1 << i) >= lvl[b]) a = par[a][i];
}
if(a == b) return a;
for(int i = mlg; i >= 0; i--) {
if(par[a][i] != par[b][i]) a = par[a][i], b = par[b][i];
}
return par[a][0];
}
bool comp(int a, int b){
return order[a]<order[b];
}
int get_ans(int a, int p){
bool ans = 0;
int total = 0;
for(auto x: g[a]){
if(x==p) continue;
int d = id[{a, x}];
int cc = get_ans(x, a);
// cout<<d<<' '<<cc<<endl;
h[d] = cc;
total += cc;
}
total += pres[a];
return total;
}
int32_t main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>m>>k;
int a, b, qt;
for(int i=0; i<n-1; i++){
cin>>a>>b;
g[a].pb(b);
g[b].pb(a);
id[{a, b}] = id[{b, a}] = i;
}
int root = 1;
dfs(root, root);
for(int i=0; i<m; i++){
cin>>qt;
int up = -1;
vi cc;
while(qt--){
cin>>a;
cc.pb(a);
pres[a]++;
}
sort(all(cc), comp);
up = cc[0];
for(int i=1; i<cc.size(); i++){
int cur_lca = lca(cc[i-1], cc[i]);
pres[cur_lca]--;
up = lca(up, cur_lca);
}
pres[up]--;
}
get_ans(root, root);
for(auto x: h){
// cout<<x.x<<' '<<x.y<<endl;
if(x.y>=k) res.insert(x.x);
}
cout<<res.size()<<endl;
for(auto x: res){
cout<<x+1<<' ';
}
}
