#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<int, int>;
//#define int ll
#define all(x) x.begin(), x.end()
#define rep(i, l, n) for (int i = l; i < (n); ++i)
#define sz(x) (int)x.size()
const char nl = '\n';
const int N = 1e5+10;
const int LOG = 17;
P edge[N];
vector<P> g[N];
vector<int> ph[N], pp[N];
int par[N][LOG], dep[N];
set<int> s[N];
void dfs(int a = 1, int p = -1) {
par[a][0] = p;
rep(i, 1, LOG) {
int x = par[a][i-1];
if (x == -1)break;
par[a][i] = par[x][i-1];
}
for (auto [i, j]: g[a]) {
if (i == p)continue;
dep[i] = dep[a]+1;
dfs(i, a);
}
}
int lca(int x, int y) {
if (dep[y] > dep[x])swap(x, y);
for (int i = LOG-1; i >= 0; --i) {
int z = par[x][i];
//if (i == 1)cout << z << nl;
if (z != -1 && dep[z] >= dep[y]) {
//cout << x << " " << " " << z << " " << i << nl;
x = z;
}
}
if (x == y)return x;
for (int i = LOG-1; i >= 0; --i) {
int a = par[x][i], b = par[y][i];
if (a != b)x = a, y = b;
}
return par[x][0];
}
int cnt[N];
void calc(int a = 1, int p = -1, int idx = -1) {
for (auto i: ph[a])
s[a].insert(i);
for (auto [i, j]: g[a]) {
if (i == p)continue;
calc(i, a, j);
if (sz(s[i]) > sz(s[a]))swap(s[a], s[i]);
for (auto k: s[i])
s[a].insert(k);
}
for (auto i: pp[a])
s[a].erase(s[a].find(i));
if (~idx)cnt[idx] = sz(s[a]);
}
void solve() {
memset(par, -1, sizeof par);
int n, m, k; cin >> n >> m >> k;
rep(i, 0, n-1) {
int u, v; cin >> u >> v;
g[u].push_back({v, i});
g[v].push_back({u, i});
edge[i] = {u, v};
}
dfs();
//cout << par[4][1] << nl;
//cout << lca(1, 4) << nl;
rep(i, 0, m) {
int x, l = -1; cin >> x;
while (x--) {
int y; cin >> y;
ph[y].push_back(i);
l = (~l?lca(y, l):y);
}
//cout << i << " " << l << nl;
pp[l].push_back(i);
}
calc();
vector<int> res;
rep(i, 0, n-1)
if (cnt[i] >= k)res.push_back(i+1);
cout << sz(res) << nl;
for (auto i: res)cout << i << " ";
cout << nl;
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
