#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5, L = 20;
int n, m, k, tim, dep[N], sz[N], pre[N], upId[N], f[N], up[L][N];
vector<pair<int, int>> adj[N];
void dfs(int u, int par, int id, int d) {
dep[u] = d;
pre[u] = tim++;
sz[u] = 1;
upId[u] = id;
for (auto &[v, idx] : adj[u]) {
if (v == par) continue;
up[0][v] = u;
dfs(v, u, idx, d + 1);
sz[u] += sz[v];
}
}
int lca(int x, int y) {
if (dep[x] < dep[y])
swap(x, y);
int dif = dep[x] - dep[y];
for (int b = 0; b < L; b++) {
if (dif & (1 << b))
x = up[b][x];
}
if (x == y)
return x;
for (int b = L - 1; b >= 0; b--) {
if (up[b][x] == up[b][y])
continue;
x = up[b][x];
y = up[b][y];
}
return up[0][x];
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int x, y;
cin >> x >> y;
x--;
y--;
adj[x].push_back(make_pair(y, i));
adj[y].push_back(make_pair(x, i));
}
tim = 0;
dfs(0, 0, -1, 0);
for (int j = 1; j < L; j++) {
for (int i = 0; i < n; i++) {
up[j][i] = up[j - 1][up[j - 1][i]];
}
}
while (m--) {
int x;
cin >> x;
vector<int> tims(x);
vector<pair<int, int>> ordP(x), ordD(x);
for (int i = 0; i < x; i++) {
int y;
cin >> y;
y--;
tims[i] = pre[y];
ordP[i] = make_pair(pre[y], y);
ordD[i] = make_pair(dep[y], y);
}
sort(tims.begin(), tims.end());
sort(ordP.begin(), ordP.end());
sort(ordD.rbegin(), ordD.rend());
for (int i = 0; i < x; i++) {
int y = ordD[i].second;
f[y]++;
int l = upper_bound(tims.begin(), tims.end(), pre[y]) - tims.begin();
int r = lower_bound(tims.begin(), tims.end(), pre[y]+sz[y]) - tims.begin();
f[y] -= r-l;
}
int l = ordP[0].second;
int r = ordP.back().second;
f[lca(l, r)]--;
}
vector<pair<int, int>> ordD(n);
for (int i = 0; i < n; i++) {
ordD[i] = make_pair(dep[i], i);
}
sort(ordD.rbegin(), ordD.rend());
vector<int> ans;
for (int i = 0; i < n; i++) {
int x = ordD[i].second;
if (f[x] >= k) ans.push_back(upId[x]);
f[up[0][x]] += f[x];
}
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (int& i : ans) {
cout << i+1 << " ";
}
cout << "\n";
}
