#include <bits/stdc++.h>
using namespace std;
#define F0R(i, n) for (int i= 0 ; i< n;i++)
#define FOR(i,j,n) for (int i = j; i< n;i++)
template<typename T>
using V = vector<T>;
using vi = V<int>;
using pi = pair<int,int>;
vi buffer;
struct STL
{
V<map<int, int>> maps;
vi id;
STL(int n) {
maps.resize(n), id.resize(n);
F0R(i, n)
id[i] = i;
}
void add(int x, int col) {
maps[id[x]][col]++;
if (maps[id[x]][col] == buffer[col])
maps[id[x]].erase(col);
}
void combine(int a, int b) {
int orgA = a, orgB = b;
a = id[a], b = id[b];
// B is small
if (maps[b].size() > maps[a].size())
swap(a,b);
for (auto [col, app] : maps[b]) {
maps[a][col] += app;
if (maps[a][col] == buffer[col])
maps[a].erase(col);
}
id[orgA] = id[orgB] = a;
}
int siz(int x) {
return maps[id[x]].size();
}
};
V<vi> colors;
V<vi> g;
STL* stl;
map<pi, int> edgeID;
vi ans;
int k;
void dfs(int x, int p) {
for (auto c : colors[x])
stl->add(x, c);
for (auto y : g[x]) {
if (y == p) continue;
dfs(y, x);
stl->combine(x, y);
}
if (p != -1 and stl->siz(x) >= k)
ans.push_back(edgeID[{x,p}]);
}
int main() {
int n, m; cin >> n >> m >> k;
g.resize(n + 1), colors.resize(n + 1), buffer.resize(m);
F0R(i, n - 1) {
int a, b; cin >> a >> b;
g[a].push_back(b);
g[b].push_back(a);
edgeID[{a,b}] = i;
edgeID[{b,a}] = i;
}
F0R(i, m) {
int d; cin >> d;
buffer[i] = d;
F0R(j, d) {
int x; cin >> x;
colors[x].push_back(i);
}
}
stl = new STL(m + n + 1);
dfs(1, -1);
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
for (auto x : ans) {
cout << x + 1 << " ";
}
}
