#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (ll)(r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (ll)(l); --x)
typedef long long ll;
typedef std::pair<int, int> pii;
typedef std::pair<ll , ll > pll;
using namespace std;
const int N = 100'010;
vector<int> cols[N];
vector<pii> A[N];
int col_cnt[N];
int n, m, k;
class s2l {
private:
int cnt_unfin = 0;
map<int, int> mp;
public:
void insert(int x, int cnt=1)
{
int &val = mp[x];
cnt_unfin += val == 0;
val += cnt;
cnt_unfin -= val == col_cnt[x];
}
void merge(s2l *that)
{
if (mp.size() < that->mp.size()) {
mp.swap(that->mp);
swap(cnt_unfin, that->cnt_unfin);
}
for (auto [x, y] : that->mp)
insert(x, y);
delete(that);
}
int get_cnt()
{
return cnt_unfin;
}
};
vector<int> ans_edges;
s2l *dfs(int v, int p)
{
s2l *ans = new s2l;
for (int c : cols[v])
ans->insert(c);
for (auto [u, e] : A[v]) {
if (e == p)
continue;
ans->merge(dfs(u, e));
}
if (p != -1 && ans->get_cnt() >= k)
ans_edges.push_back(p);
return ans;
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n >> m >> k;
Loop (i,0,n-1) {
int v, u;
cin >> v >> u;
--v; --u;
A[v].push_back({u,i});
A[u].push_back({v,i});
}
Loop (i,0,m) {
cin >> col_cnt[i];
Loop (j,0,col_cnt[i]) {
int v;
cin >> v;
cols[v-1].push_back(i);
}
}
dfs(0, -1);
sort(ans_edges.begin(), ans_edges.end());
cout << ans_edges.size() << '\n';
for (int e : ans_edges)
cout << e+1 << ' ';
cout << '\n';
}
