#include <bits/stdc++.h>
#define pb push_back
#define eb emplace_back
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define uniq(x) x.erase(unique(all(x)), x.end())
#define rall(x) x.rbegin(), x.rend()
//#define int long long
using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
const int mod = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 5;
const double eps = 1e-9;
void setIO() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
struct BIT {
int n;
vector<ll> tree, val;
void config(int _n) {
n = _n + 10;
tree.resize(_n+60);
val.resize(_n+60);
}
void add(int p, int v) {
val[p] += v;
for(p++; p<n; p+=p&-p) tree[p] += v;
}
ll sum(int p) {
ll ans = 0;
for(p++; p>0; p-=p&-p) ans += tree[p];
return ans;
}
ll query(int l, int r) { return sum(r) - sum(l-1); }
void set(int p, int v) { add(p, v - val[p]); }
};
int n, m, k, timer = 0;
int depth[maxn+1], up[maxn+1][LOG], in[maxn+1], out[maxn+1];
vector<vector<int> > graph;
vector<int> euler;
void dfs(int u, int p) {
in[u] = timer++;
euler.push_back(u);
for(int i=1; i<LOG; i++)
up[u][i] = up[ up[u][i-1] ][i-1];
for(int &v : graph[u]) {
if(v == p) continue;
depth[v] = depth[u] + 1;
up[v][0] = u;
dfs(v, u);
}
out[u] = timer;
euler.push_back(u);
}
int jmp(int x, int d) {
for(int j=LOG-1; j>=0; j--)
if(d & (1 << j)) x = up[x][j];
return x;
}
int get_lca(int a, int b) {
if(depth[a] < depth[b]) swap(a, b);
a = jmp(a, depth[a] - depth[b]);
if(a == b) return a;
for(int j=LOG-1; j>=0; j--)
if(up[a][j] != up[b][j])
a = up[a][j], b = up[b][j];
return up[a][0];
}
int32_t main() {
setIO();
cin >> n >> m >> k;
graph.resize(n+1);
vector<pii> edges;
for(int i=0; i<n-1; i++) {
int a, b;
cin >> a >> b;
edges.push_back({ a, b });
graph[a].push_back(b);
graph[b].push_back(a);
}
dfs(1, 0);
for(pii &x : edges)
if(depth[x.first] > depth[x.second]) swap(x.first, x.second);
vector<int> edge_id(n+1);
for(int i=0; i<n-1; i++)
edge_id[edges[i].second] = i+1;
BIT bit;
bit.config(2*n);
while(m--) {
int cnt;
cin >> cnt;
vector<int> v(cnt);
for(int &x : v) cin >> x;
sort(all(v), [&](int a, int b) { return in[a] < in[b]; });
v.push_back(v[0]);
for(int i=0; i<cnt; i++) {
int a = v[i], b = v[i+1], lca = get_lca(a, b);
bit.add(in[a], 1);
bit.add(in[b], 1);
bit.add(in[lca], -2);
}
}
vector<int> ans;
for(int i=1; i<=n; i++)
if(bit.query(in[i], out[i]-1) >= 2 * k) ans.push_back(edge_id[i]);
cout << sz(ans) << '\n';
sort(all(ans));
for(int &x : ans) cout << x << " ";
return 0;
}
