#include <bits/stdc++.h>
using namespace std;
#define rep(i,s,e) for (int i = s; i <= e; ++i)
#define rrep(i,s,e) for (int i = s; i >= e; --i)
#define pb push_back
#define pf push_front
#define fi first
#define se second
#define all(a) a.begin(), a.end()
typedef long long ll;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef vector<int> vi;
typedef vector<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
const int mx = 1e5, L = 30;
int par[mx+1][L], tin[mx+1], k, tt = 0, ad[mx+1], depth[mx+1];
vii neibs[mx+1];
vi ans;
int go_up (int x, int d) {
rep (i,0,L-1) {
if (d%2) x = par[x][i];
d /= 2;
}
return x;
}
int lca (int a, int b) {
if (depth[a]<depth[b]) swap(a,b);
int dif = depth[a]-depth[b];
a = go_up (a, dif);
if (a==b) return a;
rrep (i, L-1, 0) {
if (par[a][i] != par[b][i]) {
a = par[a][i];
b = par[b][i];
}
}
return par[a][0];
}
void dfs (int u) {
tin[u] = ++tt;
for (auto ve : neibs[u]) {
if (tin[ve.fi]) continue;
par[ve.fi][0] = u;
depth[ve.fi] = depth[u]+1;
dfs (ve.fi);
}
}
int dfs2 (int u) {
int x = ad[u];
for (auto ve : neibs[u]) {
if (par[u][0]==ve.fi) continue;
int res = dfs2 (ve.fi);
if (res>=k) ans.pb(ve.se);
x += res;
}
return x;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int n, m; cin >> n >> m >> k;
rep (i,1,n-1) {
int u, v; cin >> u >> v;
neibs[u].pb({v,i});
neibs[v].pb({u,i});
}
dfs(1);
par[1][0] = 1;
rep (i,1,L-1)
rep (j,1,n)
par[j][i] = par[par[j][i-1]][i-1];
rep (i,1,m) {
int s; cin >> s; int x[s];
rep (j,0,s-1) {
cin >> x[j];
ad[x[j]]++;
}
sort(x, x+s, [&](const int &a,const int &b){return tin[a]<tin[b];});
rep (j,0,s-2) ad[lca(x[j], x[j+1])]--;
ad[lca(x[0], x[s-1])]--;
}
dfs2 (1);
cout << ans.size() << "\n";
sort(all(ans));
for (int a : ans) cout << a << " ";
cout << "\n";
return 0;
}
