#include <bits/stdc++.h>
using namespace std;
// #undef _GLIBCXX_DEBUG // disable run-time bound checking, etc
// #pragma GCC optimize("Ofast,inline") // Ofast = O3,fast-math,allow-store-data-races,no-protect-parens
// #pragma GCC optimize ("unroll-loops")
// #pragma GCC target("bmi,bmi2,lzcnt,popcnt") // bit manipulation
#pragma GCC target("movbe") // byte swap
// #pragma GCC target("aes,pclmul,rdrnd") // encryption
// #pragma GCC target("avx,avx2,f16c,fma,sse3,ssse3,sse4.1,sse4.2") // SIMD
// #include <bits/extc++.h>
// using namespace __gnu_pbds;
// template<class T>using ordered_set = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
// template<class T>using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define ll long long
#define INF (ll)1e9+7
#define fo(i, n) for(int i=0;i<n;i++)
#define deb(x) cout << #x << " = " << x << endl;
#define deb2(x, y) cout << #x << " = " << x << ", " << #y << " = " << y << endl
#define pb push_back
#define mp make_pair
#define F first
#define S second
#define LSOne(S) ((S) & (-S))
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
inline int readint(){ int v = 0; char c; while((c = getchar()) != EOF && c != ' ' && c != '\n'){ v *= 10; v += c - '0'; } return v; }
inline int readintsigned() { int v = 0; int sign = 1; char c = getchar(); if (c == '-') { sign = -1; } else { v += c - '0'; } while ((c = getchar()) != EOF && c != ' ' && c != '\n') { v *= 10; v += c - '0'; } return v * sign; }
inline string readstring() { string s; char c; while ((c = getchar()) != EOF && c != '\n' && c != ' ') { s.push_back(c); } return s; }
template <class result_t=std::chrono::milliseconds,class clock_t=std::chrono::steady_clock,class duration_t = std::chrono::milliseconds>
auto since(std::chrono::time_point<clock_t, duration_t> const& start){return std::chrono::duration_cast<result_t>(clock_t::now() - start);}
typedef pair<int, int> pii;
typedef pair<ll, ll> pl;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef vector<pii> vpii;
typedef vector<pl> vpl;
typedef vector<vi> vvi;
typedef vector<vl> vvl;
typedef vector<vpii> vvpii;
typedef vector<vpl> vvpl;
vvi adj(100001);
vl d(100001);
vpl order;
void dfs(int pos, int last = -1, int depth = 0){
d[pos] = depth;
for(auto u : adj[pos]){
if(u == last) continue;
dfs(u, pos, depth+1);
}
order.pb({depth, pos});
}
int main() {
// cout << fixed << setprecision(20);
// auto start = std::chrono::steady_clock::now(); // since(start).count()
cin.tie(0)->sync_with_stdio(0);
int n, m, k, a, val, from, to;
cin >> n >> m >> k;
map<pl, ll> toRoad;
fo(i, n-1){
cin >> from >> to;
adj[--from].pb(--to);
adj[to].pb(from);
toRoad[{from, to}] = i+1;
toRoad[{to, from}] = i+1;
}
dfs(0);
vvl bl(24, vl(100001, 0));
fo(i, adj.size()){
for(auto v : adj[i]){
if(d[v] >= d[i]) continue;
bl[0][i] = v;
}
}
fo(i, 22){
fo(j, n){
bl[i+1][j] = bl[i][bl[i][j]];
}
}
vvl root(100001);
vector<set<ll>> wantRoad(100001);
fo(x, m){
cin >> a;
vl v;
fo(y, a){
cin >> val;
val--;
v.pb(val);
wantRoad[val].insert(x);
}
ll deapest = v[0];
fo(i, a){
if(!i) continue;
ll current = v[i];
if(d[current]<d[deapest]) swap(deapest, current);
for(int m = d[current]-d[deapest];m;m-=LSOne(m)){
current = bl[__builtin_ctz(LSOne(m))][current];
}
if(current == deapest) continue;
for(int j = 22; j>=0;j--){
if(bl[j][current] == bl[j][deapest]) continue;
current = bl[j][current];
deapest = bl[j][deapest];
}
current = bl[0][current];
deapest = bl[0][deapest];
}
root[deapest].pb(x);
}
vl ans;
sort(rall(order));
for(auto ver : order){
if(!ver.S) continue;
for(auto toRem : root[ver.S]){
wantRoad[ver.S].erase(toRem);
}
if(wantRoad[ver.S].size() >= k) ans.pb(toRoad[{ver.S, bl[0][ver.S]}]);
if(wantRoad[ver.S].size() > wantRoad[bl[0][ver.S]].size()) swap(wantRoad[ver.S], wantRoad[bl[0][ver.S]]);
for(auto ve : wantRoad[ver.S]){
wantRoad[bl[0][ver.S]].insert(ve);
}
}
sort(all(ans));
cout << ans.size() << "\n";
fo(i, ans.size()){
cout << ans[i] << " ";
}
return 0;
}
