#include <bits/stdc++.h>
#define int long long
// #pragma GCC ("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define all(x) x.begin(), x.end()
#define kill(x) cout << x << "\n", exit(0);
#define pii pair<int, int>
#define pll pair<long long, long long>
#define endl "\n"
using namespace std;
typedef long long ll;
typedef __int128_t lll;
typedef long double ld;
const int MAXN = (int)1e6 + 7;
const ll MOD = (int)1e9 + 7;
const int INF = (int)1e9 + 7;
const int LG = 20;
int n, m, k, t, tmp, tmp2, tmp3, tmp4, u, v, w, flag, q, ans;
int arr[MAXN], st[MAXN], ft[MAXN], blk[MAXN], sz[MAXN], h[MAXN], par[MAXN];
int pow2dad[MAXN][LG], edge_id[MAXN], res[MAXN], ind[MAXN];
vector<int> adj[MAXN], final_res;
vector<pii> edge, vec;
/* Segment Tree */
#define mid ((l+r)>>1)
#define lid (id<<1)
#define rid (lid|1)
int seg[MAXN<<2], lazy[MAXN<<2];
inline void relax(int l, int r, int id) {
if (lazy[id] == 0) return;
seg[lid] += lazy[id]*(mid-l); lazy[lid] += lazy[id];
seg[rid] += lazy[id]*(r-mid); lazy[rid] += lazy[id];
lazy[id] = 0;
}
void upd(int s, int t, int l=0, int r=n, int id=1) {
if (s >= t) return;
if (s <= l && t >= r) {
seg[id] += r-l; lazy[id]++;
return;
}
relax(l, r, id);
if (s < mid) upd(s, t, l, mid, lid);
if (t > mid) upd(s, t, mid, r, rid);
seg[id] = seg[lid]+seg[rid];
}
void rebuild(int l=0, int r=n, int id=1) {
if (l+1 == r) {
res[ind[l]] = seg[id];
return;
}
relax(l, r, id);
rebuild(l, mid, lid);
rebuild(mid, r, rid);
}
/* Segment Tree */
/* LCA */
inline int up(int v, int k) {
for (int i=LG-1; i>=0; i--) {
if (k >= (1<<i)) {
v = pow2dad[v][i];
k -= (1<<i);
}
}
return v;
}
inline int LCA(int u, int v) {
if (h[u] < h[v]) swap(u, v);
u = up(u, h[u]-h[v]);
for (int i=LG-1; i>=0; i--) {
if (h[u] >= (1<<i) && pow2dad[u][i] != pow2dad[v][i]) {
u = pow2dad[u][i];
v = pow2dad[v][i];
}
}
if (u == v) return u;
return par[v];
}
/* LCA */
/* HLD */
void DFSsz(int v) {
sz[v] = 1;
for (int u:adj[v]) {
if (u == par[v]) continue;
par[u] = v; h[u] = h[v]+1;
DFSsz(u);
sz[v] += sz[u];
}
}
void DFS(int v, int head) {
st[v] = flag; ind[flag++] = v; blk[v] = head;
int big = 0;
for (int u:adj[v]) if (u != par[v] && sz[u] > sz[big]) big = u;
if (big) DFS(big, head);
for (int u:adj[v]) if (u != par[v] && u != big) DFS(u, u);
ft[v] = flag;
}
void inc_direct_path(int u, int v) {
if (blk[u] != blk[v]) {
upd(st[blk[u]], st[u]+1);
inc_direct_path(par[blk[u]], v);
} else {
upd(st[v]+1, st[u]+1);
}
}
inline void inc_path(int u, int v) {
if (h[u] < h[v]) swap(u, v);
int lca = LCA(u, v);
if (lca == v) inc_direct_path(u, v);
else inc_direct_path(u, lca), inc_direct_path(v, lca);
}
/* HLD */
int32_t main() {
#ifdef LOCAL
freopen("inp.in", "r", stdin);
freopen("res.out", "w", stdout);
#else
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#endif
cin >> n >> q >> k;
for (int i=1; i<n; i++) {
cin >> u >> v;
edge.pb({u, v}); adj[u].pb(v); adj[v].pb(u);
}
DFSsz(1);
for (int i=0; i<n-1; i++) {
u = edge[i].F; v = edge[i].S;
if (h[u] < h[v]) swap(u, v);
edge_id[u] = i+1;
}
DFS(1, 1);
for (int i=1; i<=n; i++) pow2dad[i][0] = par[i];
for (int j=1; j<LG; j++) for (int i=1; i<=n; i++) pow2dad[i][j] = pow2dad[pow2dad[i][j-1]][j-1];
for (int i=1; i<=q; i++) {
cin >> m; vec.clear();
for (int j=1; j<=m; j++) {
cin >> u;
vec.pb({st[u], u});
}
sort(all(vec));
for (int j=0; j<m-1; j++) inc_path(vec[j].S, vec[j+1].S);
inc_path(vec[0].S, vec[m-1].S);
}
rebuild();
for (int i=1; i<=n; i++) if (res[i] >= 2*k) final_res.pb(edge_id[i]);
sort(all(final_res));
cout << final_res.size() << endl;
for (auto cur:final_res) cout << cur << " ";
cout << endl;
return 0;
}
