#include <bits/stdc++.h>
// Author: Kazuki_Will_Win_VOI_8703
#define fi first
#define se second
#define pii pair<int, int>
#define int long long
#define all(a) a.begin(), a.end()
using namespace std;
const int mn = 2e5 + 5, B = 450, nB = 3005, lg2 = 20, mbit = (1 << 20) + 1, mm = 5e3 + 5, mod = 1e6 + 3, inf = 1e18;
int n, m, k, st[mn], ft[mn], up[mn][20], id[mn], d[mn], timer = 0, dp[mn];
vector <pii> a[mn];
void pre_dfs(int u, int p){
st[u] = ++ timer;
for(auto [v, i] : a[u]){
if(v == p) continue;
id[v] = i;
up[v][0] = u;
d[v] = d[u] + 1;
for(int i = 1; i <= 16; i++){
if(up[v][i - 1] != -1) up[v][i] = up[up[v][i - 1]][i - 1];
}
pre_dfs(v, u);
}
ft[u] = timer;
}
int lca(int u, int v){
if(d[u] < d[v]) swap(u, v);
int kc = d[u] - d[v];
for(int i = 16; i >= 0; i--){
if(kc & (1 << i)) u = up[u][i];
}
if(u == v) return u;
for(int i = 16; i >= 0; i--){
if(up[u][i] != -1 && up[v][i] != -1 && up[u][i] != up[v][i]){
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
bool cmp(int u, int v){
return st[u] < st[v];
}
void dfs2(int u, int p){
for(auto [v, i] : a[u]){
if(v == p) continue;
dfs2(v, u);
dp[u] += dp[v];
}
}
void solve(){
cin >> n >> m >> k;
for(int i = 1; i < n; i++){
int u, v; cin >> u >> v;
a[u].push_back({v, i});
a[v].push_back({u, i});
}
memset(up, -1, sizeof(up));
pre_dfs(1, 0);
for(int i = 1; i <= m; i++){
int s; cin >> s;
vector <int> pts;
for(int i = 1; i <= s; i++){
int u; cin >> u;
pts.push_back(u);
}
sort(all(pts), cmp);
pts.push_back(pts[0]);
for(int j = 0; j < s; j++){
int u = pts[j], v = pts[j + 1];
// cout << u << ' ' << v << ' ' << lca(u, v) << '\n';
dp[u] ++, dp[v] ++, dp[lca(u, v)] -= 2;
}
}
// cout << dp[4] << ' ' << dp[5] << ' ' << dp[6] << '\n';
dfs2(1, 0);
vector <int> ans;
for(int i = 2; i <= n; i++){
if(dp[i] >= 2 * k) ans.push_back(id[i]);
}
sort(all(ans));
cout << ans.size() << '\n';
for(auto i : ans) cout << i << ' ';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
int t = 1;
// cin >> t;
while(t--) solve();
}
