#include<bits/stdc++.h>
using namespace std;
vector<int> dep, pos, par, val, eul;
vector<vector<int>> adj;
struct sparse {
int n, m;
vector<vector<int>> sp;
int high(int a, int b) {
return (dep[a]<=dep[b]?a:b);
}
void build() {
m=0; n=eul.size();
while ((1<<m)<n) m++;
sp.assign(m, vector<int>(n, 0));
for (int i = 0; i < n; ++i) sp[0][i]=eul[i];
for (int i = 1; i < m; ++i) {
for (int j = 0; j < n-(1<<i)+1; ++j) {
sp[i][j]=high(sp[i-1][j], sp[i-1][j+(1<<i-1)]);
}
}
}
int query(int a, int b) {
if (a==b) return a;
a=pos[a], b=pos[b];
if (a>b) swap(a, b);
int d=b-a, t=0;
while ((1<<t)<=d) t++; t--;
return high(sp[t][a], sp[t][b-(1<<t)+1]);
}
} sp;
bool pcomp(int a, int b) { return pos[a]<pos[b]; }
void dvts(vector<int>& ic) {
int n=ic.size();
sort(ic.begin(), ic.end(), pcomp);
val[ic[0]]++; val[sp.query(ic[0], ic[n-1])]--;
for (int i = 1; i < n; ++i) {
val[ic[i]]++;
val[sp.query(ic[i], ic[i-1])]--;
}
}
void tour(int u, int p) {
par[u]=p;
dep[u]=dep[p]+1;
pos[u]=eul.size();
eul.push_back(u);
for (auto v : adj[u]) {
if (v==p) continue;
tour(v, u);
eul.push_back(u);
}
}
void fill(int u, int p) {
for (auto v : adj[u]) {
if (v==p) continue;
fill(v, u);
val[u]+=val[v];
}
}
int main() {
cin.tie(0)->sync_with_stdio(false);
int n, m, k;
cin >> n >> m >> k;
map<pair<int, int>, int> eord;
adj.assign(n+1, vector<int>());
for (int i = 0; i < n-1; ++i) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
if (a<b) swap(a, b);
eord[{a, b}]=i+1;
}
pos.assign(n+1, 0);
dep.assign(n+1, 0);
par.assign(n+1, 0);
tour(1, 1);
sp.build();
val.assign(n+1, 0);
for (int i = 0, s; i < m; ++i) {
cin >> s;
vector<int> c(s);
for (int i = 0; i < s; ++i) {
cin >> c[i];
} dvts(c);
} fill(1, 1);
vector<int> ans;
for (int i = 1; i <= n; ++i) {
if (val[i]<k) continue;
int a=i, b=par[i];
if (a<b) swap(a, b);
ans.push_back(eord[{a, b}]);
}
cout << ans.size() << '\n';
for (auto i : ans) {
cout << i << ' ';
} cout << '\n';
return 0;
}
