#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ull, ull> pull;
typedef pair<int, int> pii;
typedef pair<ld, ld> pld;
int n, m, k;
vector<pii> g[100009];
vector<int> s[100009];
int totcnt[100009];
struct node{
map<int, int> cnt;
int all = 0;
};
node nd[100009];
void merge(node &a, node &b){
if(b.cnt.size() > a.cnt.size())
swap(a, b);
for(auto u : b.cnt){
assert(u.ss);
a.cnt[u.ff] += u.ss;
if(a.cnt[u.ff] == totcnt[u.ff])
a.all++;
}
}
vector<int> ans;
void dfs(int v, int prt){
for(auto u : s[v])
nd[v].cnt[u]++;
for(auto u : nd[v].cnt)
if(u.ss == totcnt[u.ff])
nd[v].all++;
for(auto u : g[v]){
if(u.ss == prt) continue;
dfs(u.ff, u.ss);
merge(nd[v], nd[u.ff]);
}
//cout << v << ' ' << prt << ' ' << nd[v].cnt.size() << '\n';
if((int)nd[v].cnt.size()-nd[v].all >= k && prt)
ans.pb(prt);
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
cin >> n >> m >> k;
for(int i = 1; i < n; ++i){
int x, y;
cin >> x >> y;
g[x].pb({y, i});
g[y].pb({x, i});
}
for(int i = 0; i < m; ++i){
int num;
cin >> num;
totcnt[i] = num;
while(num--){
int tmp;
cin >> tmp;
s[tmp].pb(i);
}
}
dfs(1, 0);
cout << ans.size() << '\n';
sort(all(ans));
for(auto u : ans)
cout << u << ' ';
}
