#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define gcd __gcd
#define sz(v) (int) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define dbg(x) "[" #x " = " << (x) << "]"
///#define int long long
using ll = long long;
using ld = long double;
using ull = unsigned long long;
template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}
const int N = 1e5+5;
const int lg = 21;
int n, m, k, timerDFS, h[N];
int tin[N], tout[N], par[lg][N], val[N];
pair<int,int> E[N];
vector<int> g[N], answer;
void pre_dfs(int x, int p){
tin[x] = ++timerDFS;
for(int id : g[x]){
int v = E[id].first ^ E[id].second ^ x;
if(v != p){
h[v] = h[x] + 1;
par[0][v] = x;
for(int i = 1; i < lg; i++) par[i][v] = par[i-1][par[i-1][v]];
pre_dfs(v, x);
}
}
tout[x] = timerDFS;
return;
}
bool inSub(int u, int v){
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
bool cmpDFS(int u, int v){
return tin[u] < tin[v];
}
int get_LCA(int u, int v){
if(h[u] < h[v]) swap(u, v);
int k = h[u] - h[v];
for(int i = lg-1; i >= 0; i--) if(k>>i&1) u = par[i][u];
if(u == v) return v;
for(int i = lg-1; i >= 0; i--) if(par[i][u] != par[i][v]) u = par[i][u], v = par[i][v];
return par[0][v];
}
void solve_Query(vector<int>& vec){
sort(all(vec), cmpDFS);
int k = sz(vec);
for(int i = 1; i < k; i++) vec.pb(get_LCA(vec[i], vec[i-1]));
sort(all(vec), cmpDFS), compact(vec);
stack<int> st; st.push(vec[0]);
for(int i = 1; i < sz(vec); i++){
int v = vec[i];
while(!inSub(st.top(), v)) st.pop();
val[v]++, val[st.top()]--;
st.push(v);
}
return;
}
void proc_val(int x, int p){
for(int id : g[x]){
int v = E[id].first ^ E[id].second ^ x;
if(v != p){
proc_val(v, x);
val[x] += val[v];
if(val[v] >= k) answer.push_back(id);
}
}
return;
}
void solve()
{
cin >> n >> m >> k;
for(int i = 1; i < n; i++){
int u,v; cin >> u >> v;
E[i] = make_pair(u, v);
g[u].pb(i), g[v].pb(i);
}
pre_dfs(1, -1);
for(int i = 1; i <= m; i++){
int k; cin >> k;
vector<int> vec;
for(int j = 1; j <= k; j++){
int v; cin >> v;
vec.push_back(v);
}
solve_Query(vec);
}
proc_val(1, -1);
cout << sz(answer) <<"\n";
sort(all(answer));
for(int id : answer) cout << id <<" "; cout <<"\n";
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
#define name "InvMOD"
if(fopen(name".INP", "r")){
freopen(name".INP","r",stdin);
freopen(name".OUT","w",stdout);
}
int t = 1; //cin >> t;
while(t--) solve();
return 0;
}
