/// I'm only brave when I have to be
#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ppb pop_back
#define fast_io ios::sync_with_stdio(false);cin.tie(NULL);
#define file_io freopen("input.txt","r",stdin);freopen("output.txt","w",stdout);
#define FOR(i,k,n) for(int i = k; i < n; ++ i)
#define debf cout<<"(0-0)\n";
#define all(x) x.begin(), x.end()
#define dec(x) cout << fixed << setprecision(x);
#define pf push_front
#define ppf pop_front
#define dash " ------- "
#define what(x) cerr << #x << " is " << x << endl;
#define eb emplace_back
//#define int short int
//#define int long long
#define sz(s) (int) (s.size())
#define fl cout.flush()
using namespace std;
typedef long long ll;
typedef pair <int, int> pii;
typedef pair <int, pii> pip;
typedef pair <pii, int> ppi;
typedef pair <ll, ll> pll;
typedef unsigned long long ull;
typedef long double ld;
template <class T> using max_heap = priority_queue <T, vector <T>, less <T> >;
template <class T> using min_heap = priority_queue <T, vector <T>, greater <T> >;
constexpr int MOD = 1e9 + 7, N = 1e5 + 8, M = 1e9, SQ = 300, INF = 1e9 + 8, LGN = 22, mod = 998244353, P = 131113;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int n, m, k, sz[N];
vector <int> ans;
vector <pii> v[N];
set <pii> s[N];
void dfs (int u, int par = -1, int e = -1){
for (pii i : v[u]){
if (i.F != par){
dfs (i.F, u, i.S);
if (s[i.F].size() > s[u].size()){
s[i.F].swap(s[u]);
}
for (pii p : s[i.F]){
auto p2 = s[u].lower_bound({p.F, -1});
if (p2 == s[u].end() || p2->F != p.F){
s[u].insert(p);
continue;
}
s[u].erase(p2);
pii p3 = p;
p3.S += p2->S;
if (p3.S != sz[p.F]){
s[u].insert(p3);
}
}
}
}
if (s[u].size() >= k){
ans.pb(e);
}
return;
}
int32_t main(){
fast_io;
cin >> n >> m >> k;
for (int i = 0; i < n - 1; ++ i){
int aa, bb;
cin >> aa >> bb;
v[--aa].pb({--bb, i});
v[bb].pb({aa, i});
}
FOR (i, 0, m){
int ss, aa;
cin >> ss;
sz[i] = ss;
for (int j = 0; j < ss; ++ j){
cin >> aa;
if (ss != 1){
s[--aa].insert({i, 1});
}
}
}
dfs (0);
sort (all(ans));
cout << ans.size() << '\n';
for (int i : ans){
cout << i + 1 << " ";
}
return 0;
}
// Yesterday is history
// Tomorrow is a mystery
// but today is a gift
// That is why it is called the present
