#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<double> vd;
typedef vector<string> vs;
typedef vector<ll> vll;
const int mx = 1e5, mx2 = 30;
int tin[mx+1], tout[mx+1], tt, par[mx+1][mx2+1], k, go[mx+1];
vector<int> lca[mx+1], blebs[mx+1], ans;
vii neibs[mx+1];
set<int> st[mx+1];
void dfs (int u) {
tin[u] = ++tt;
for (auto vi : neibs[u]) {
if (tin[vi.fi]) continue;
par[vi.fi][0] = u;
dfs (vi.fi);
}
tout[u] = tt;
}
void dfs2 (int u) {
int best = 0;
for (auto vi : neibs[u]) {
if (vi.fi==par[u][0]) continue;
dfs2 (vi.fi);
if ((int)st[go[vi.fi]].size()>=k) ans.pb(vi.se);
if (st[go[vi.fi]].size()>st[go[best]].size()) best = vi.fi;
}
go[u] = (best?go[best]:u);
for (int bleb : blebs[u]) st[go[u]].insert(bleb);
for (auto vi : neibs[u]) {
if (vi.fi==par[u][0] || vi.fi==best) continue;
for (int bleb : st[go[vi.fi]]) st[go[u]].insert(bleb);
}
for (int l : lca[u]) st[go[u]].erase(l);
}
int go_up (int x, int d) {
rep (i,0,mx2) {
if (d%2) x = par[x][i];
d /= 2;
}
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});
}
par[1][0] = 1;
dfs (1);
rep (i,1,mx2)
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+1], mi = 1e9, ma = 0;
rep (j,1,s) {
cin >> x[j];
blebs[x[j]].pb(i);
mi = min(mi, tin[x[j]]);
ma = max(ma, tout[x[j]]);
}
int lo = 0, hi = n-1;
while (lo<hi) {
int mid = (lo+hi)/2;
int y = go_up(x[1],mid);
if (tin[y]<=mi && tout[y]>=ma) hi = mid;
else lo = mid+1;
}
lca[go_up(x[1],lo)].pb(i);
}
dfs2 (1);
cout << ans.size() << "\n";
sort(all(ans));
for (int x : ans) cout << x << " ";
cout << "\n";
return 0;
}
