/* be name khoda */
#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
using namespace std;
#define forifrom(i, s, n) for (ll i = (s); i < (n); ++i)
#define fori(i, n) forifrom(i, 0, n)
#define forirto(i, n, e) for (ll i = (n) - 1; i >= (e); --i)
#define forir(i, n) forirto(i, n, 0)
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define F first
#define S second
typedef long long ll;
typedef pair<ll, ll> pii;
typedef vector<ll> vi;
typedef vector<pii> vpii;
const ll maxn = 100010;
const ll maxnlg = 20;
ll n, m, k;
vpii g[maxn];
ll st[maxn], ft[maxn], pars[maxnlg][maxn];
vi vers;
ll ps[maxn];
ll es[maxn];
ll tim = 0;
void dfs_stft(ll x, ll par) {
st[x] = tim++;
pars[0][x] = par;
fori (i, maxnlg - 1) {
pars[i + 1][x] = pars[i][pars[i][x]];
}
for (auto y : g[x]) {
if (y.F != par) {
dfs_stft(y.F, x);
}
}
ft[x] = tim;
}
ll LCA(ll a, ll b) {
if (st[a] > st[b]) swap(a, b);
if (ft[a] >= ft[b]) return a;
forir (i, maxnlg) {
if (ft[pars[i][a]] < ft[b]) a = pars[i][a];
}
return pars[0][a];
}
void add_path(ll a, ll b, ll d) {
ps[a] += d;
ps[b] += d;
ps[LCA(a, b)] -= 2 * d;
}
bool st_cmp(ll a, ll b) {
return st[a] < st[b];
}
void dfs_sum(ll x, ll par) {
for (auto y : g[x]) {
if (y.F != par) {
dfs_sum(y.F, x);
ps[x] += ps[y.F];
es[y.S] += ps[y.F];
}
}
}
int main() {
ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
cin >> n >> m >> k;
fori (i, n - 1) {
ll a, b; cin >> a >> b;;
g[a].pb({b, i}), g[b].pb({a, i});
}
g[0].pb({1, n});
dfs_stft(0, 0);
fori (i, m) {
ll c; cin >> c;
vers.clear();
fori (j, c) {
ll x; cin >> x;
vers.pb(x);
}
if (c == 1) continue;
sort(all(vers), st_cmp);
add_path(vers[0], vers.back(), 2);
forifrom (i, 1, vers.size() - 1) {
add_path(vers[i - 1], vers[i], 1);
add_path(vers.back(), vers[i], 1);
add_path(vers[i - 1], vers.back(), -1);
}
}
dfs_sum(0, 0);
ll ans = 0;
fori (i, n - 1) {
if (es[i] >= k * 2) ++ans;
}
cout << ans << '\n';
fori (i, n - 1) {
if (es[i] >= k * 2) cout << i + 1 << ' ';
}
cout << '\n';
}
/*
6 3 2
1 3
2 3
3 4
6 4
4 5
4 1 3 2 5
2 6 3
2 3 2
*/
