#include <bits/stdc++.h>
using namespace std;
template<typename T>
void out(T x) { cout << x << endl; exit(0); }
#define watch(x) cout << (#x) << " is " << (x) << endl
const int maxn = 1e5+10;
int n, m, k;
vector<pair<int,int>> g[maxn];
set<int> nodes[maxn];
const int LOG = 19;
int par[LOG+1][maxn];
int dep[maxn];
int lca(int u, int v) {
if (dep[u]<dep[v]) swap(u,v);
int dx = dep[u]-dep[v];
for (int j=0; j<LOG; j++) {
if (dx>>j&1) {
u = par[j][u];
}
}
if (u==v) return v;
for (int j=LOG-1; j>=0; j--) {
if (par[j][u] != par[j][v]) {
u = par[j][u];
v = par[j][v];
}
}
return par[0][u];
}
int tin[maxn];
int tout[maxn];
int cloc = 1;
void dfs(int at, int p) {
for (int j=1; j<LOG; j++) {
par[j][at] = par[j-1][par[j-1][at]];
}
tin[at] = cloc++;
for (auto ed: g[at]) {
int to = ed.second;
if (to == p) continue;
dep[to]=1+dep[at];
par[0][to] = at;
dfs(to, at);
}
tout[at] = cloc++;
}
vector<int> add[maxn], sub[maxn];
vector<int> ans;
set<int> dfs2(int at, int p, int edId=0) {
set<int> res;
for (auto ed: g[at]) {
int idx = ed.first;
int to = ed.second;
if (to==p) continue;
auto ret = dfs2(to, at, idx);
if (res.size() < ret.size()) {
swap(res, ret);
}
res.insert(ret.begin(), ret.end());
}
for (int x: add[at]) {
res.insert(x);
}
for (int x: sub[at]) {
res.erase(x);
}
if ((int)res.size() >= k && edId!=0) ans.push_back(edId);
return res;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin>>n>>m>>k;
for (int i=1; i<n; i++) {
int u,v; cin>>u>>v;
g[u].push_back({i,v});
g[v].push_back({i,u});
}
for (int i=1; i<=m; i++) {
int t;
cin>>t;
while (t--) {
int x;
cin>>x;
nodes[i].insert(x);
}
}
dfs(1,0);
for (int i=1; i<=m; i++) {
int top = *nodes[i].begin();
for (int x: nodes[i]) {
add[x].push_back(i);
top = lca(top, x);
}
sub[top].push_back(i);
}
dfs2(1,0);
cout<<ans.size()<<endl;
for (int i: ans) cout<<i<<" ";
cout<<endl;
return 0;
}
