#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5;
int n, m, k, ttime, cur_chain = 1, th[maxn + 1];
int child[maxn + 1], par[maxn + 1], in[maxn + 1], out[maxn + 1], chain_id[maxn + 1], chain_head[maxn + 1], re[maxn + 1];
vector<pair<int, int>> adj[maxn + 1];
inline void DFS(int u, int p){
par[u] = p;
child[u] = 1;
for (auto [v, id] : adj[u]) if (v != p){
th[v] = id;
DFS(v, u);
child[u] += child[v];
}
return;
}
inline void hld(int u, int p){
if (chain_head[cur_chain] == 0){
chain_head[cur_chain] = u;
}
in[u] = ++ttime;
re[ttime] = u;
chain_id[u] = cur_chain;
int mx = -1;
for (auto [v, id] : adj[u]) if (v != p){
if (mx == -1 || child[v] > child[mx]) mx = v;
}
if (mx != -1) hld(mx, u);
for (auto [v, id] : adj[u]) if (v != p && v != mx){
++cur_chain;
hld(v, u);
}
out[u] = ttime;
return;
}
struct SEGMENT_TREE{
vector<int> st;
inline void init(int n){
st.resize(4 * n + 4, 0);
}
inline void update(int ind, int l, int r, int lb, int rb, int val){
if (lb > rb) return;
if (l >= lb && r <= rb){
st[ind] += val;
return;
}
int mid = (l + r) >> 1;
if (mid >= lb) update(ind << 1, l, mid, lb, rb, val);
if (mid < rb) update(ind << 1 | 1, mid + 1, r, lb, rb, val);
return;
}
inline int get(int ind, int l, int r, int pos){
if (l == r) return st[ind];
int mid = (l + r) >> 1;
if (mid >= pos) return st[ind] + get(ind << 1, l, mid, pos);
else return st[ind] + get(ind << 1 | 1, mid + 1, r, pos);
}
} seg;
inline int ancestor(int u, int v){
while (chain_id[u] != chain_id[v]){
if (chain_id[u] < chain_id[v]) swap(u, v);
while(chain_id[u] > chain_id[v]){
u = par[chain_head[chain_id[u]]];
}
}
if (in[u] > in[v]) return v;
return u;
}
inline void increase(int u, int v){
while (chain_id[u] != chain_id[v]){
if (chain_id[u] < chain_id[v]) swap(u, v);
while(chain_id[u] > chain_id[v]){
seg.update(1, 1, n, in[chain_head[chain_id[u]]], in[u], 1);
u = par[chain_head[chain_id[u]]];
}
}
if (in[u] > in[v]) swap(u, v);
if (in[u] < in[v]) {
seg.update(1, 1, n, in[u] + 1, in[v], 1);
}
return;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> m >> k;
seg.init(n);
for (int i = 1, u, v; i < n; ++i){
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
DFS(1, -1);
hld(1, -1);
for (int i = 1; i <= m; ++i){
int num; cin >> num;
vector<int> v(num);
for (int i = 0; i < num; ++i) cin >> v[i];
sort(v.begin(), v.end(), [](int x, int y){
return in[x] < in[y];
});
for (int i = 1; i < num; ++i) v.push_back(ancestor(v[i - 1], v[i]));
sort(v.begin(), v.end(), [](int x, int y){
return in[x] < in[y];
});
v.erase(unique(v.begin(), v.end()), v.end());
stack<int> st;
for (int i = 0; i < v.size(); ++i){
while (!st.empty()){
int cur = st.top();
if (!(in[cur] <= in[v[i]] && out[v[i]] <= out[cur])) st.pop();
else break;
}
if (!st.empty()){
int cur = st.top();
increase(cur, v[i]);
}
st.push(v[i]);
}
}
vector<int> res;
for (int i = 2; i <= n; ++i) if (seg.get(1, 1, n, i) >= k)
res.push_back(th[re[i]]);
sort(res.begin(), res.end());
cout << res.size() << '\n';
for (int x : res) cout << x << ' ';
return 0;
}
