#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define ff first
#define ss second
#define pii pair<int, int>
#define sz(v) (int)(v).size()
#define all(v) (v).begin(), (v).end()
int k, tim;
vector<int> d, p, tin, tout, ans;
vector<vector<int>> sp;
vector<vector<pii>> E;
void dfs(int x, int pr) {
sp[x][0] = pr;
tin[x] = ++tim;
if (~pr) d[x] = d[pr] + 1;
for (auto [i, w] : E[x])
if (i != pr) dfs(i, x);
tout[x] = ++tim;
}
int lca(int x, int y) {
if (d[x] < d[y]) swap(x, y);
for (int i = 20; i >= 0; i--)
if (d[x] - (1 << i) >= d[y]) x = sp[x][i];
if (x == y) return x;
for (int i = 20; i >= 0; i--) {
if (sp[x][i] != sp[y][i]) {
x = sp[x][i]; y = sp[y][i];
}
}
return sp[x][0];
}
int dfs1(int x, int pr) {
int sm = p[x];
for (auto [i, ind] : E[x]) {
if (i != pr) {
int y = dfs1(i, x);
if (k <= p[x] + y) ans.push_back(ind);
sm += y;
}
}
return sm;
}
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int n, m;
cin >> n >> m >> k;
E.assign(n, {});
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y; x--; y--;
E[x].push_back({y, i});
E[y].push_back({x, i});
}
d = tin = tout = vector<int>(n);
sp.assign(n, vector<int>(20, -1));
dfs(0, -1);
for (int i = 1; i < 20; i++) {
for (int j = 0; j < n; j++)
if (~sp[j][i - 1]) sp[j][i] = sp[sp[j][i - 1]][i - 1];
}
p.assign(n, 0);
while (m--) {
int z;
cin >> z;
// cout << "\nz " << z << endl;
int lc = 0;
set<pii> s;
vector<int> a(z);
for (int i = 0; i < z; i++) {
cin >> a[i]; a[i]--;
lc = (i ? lca(lc, a[i]) : a[i]);
s.insert({tin[a[i]], tout[a[i]]});
// cout << a[i] + 1 << ' ' << lc + 1 << endl;
}
// cout << endl;
int cnt = 0;
for (auto i : a) {
auto t = s.lower_bound({tin[i] + 1, 0});
if (t != s.end() && (*t).ss < tout[i]) continue;
// cout << i + 1 << ' ';
cnt++;
p[i]++;
}
// cout << endl << lc + 1 << ' ' << cnt << endl;
p[lc] -= cnt - 1;
if (~sp[lc][0]) p[sp[lc][0]]--;
}
// for (int i = 0; i < n; i++)
// cout << p[i] << " \n"[i + 1 == n];
dfs1(0, -1);
cout << sz(ans) << '\n';
for (auto i : ans)
cout << i << ' ';
}
