#include <bits/stdc++.h>
using namespace std;
const int logn = 20;
vector<vector<pair<int, int>>> g;
vector<vector<int>> lca;
vector<int> h1, h2, ert;
vector<bool> volt;
int hely = 0;
void bejar(int akt, int os){
volt[akt] = true;
h1[akt] = hely++;
lca[akt][0] = os;
for(pair<int, int> e : g[akt])
if(!volt[e.first])
bejar(e.first, akt);
h2[akt] = hely++;
return;
}
int get_lca(int a, int b){
if(h1[a] > h1[b]) swap(a, b);
if(h1[a] < h1[b] && h2[b] < h2[a])
return a;
for(int i = logn-1; i >= 0; i--)
if(h2[lca[a][i]] < h2[b])
a = lca[a][i];
return lca[a][0];
}
vector<int> ki;
int bejar2(int akt, int k, int el){
volt[akt] = true;
int ret = ert[akt];
for(pair<int, int> e : g[akt])
if(!volt[e.first])
ret += bejar2(e.first, k, e.second);
if(ret >= k)
ki.push_back(el);
return ret;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin>>n>>m>>k;
g.resize(n);
h1.resize(n);
h2.resize(n);
ert.resize(n, 0);
volt.assign(n, false);
lca.resize(n, vector<int>(logn));
for(int i = 0; i < n-1; i++){
int a, b;
cin>>a>>b;
g[a-1].emplace_back(b-1, i+1);
g[b-1].emplace_back(a-1, i+1);
}
bejar(0, 0);
for(int j = 1; j < logn; j++)
for(int i = 0; i < n; i++)
lca[i][j] = lca[lca[i][j-1]][j-1];
for(int i = 0; i < m; i++){
int a;
cin>>a;
vector<int> v(a);
for(int &x : v){
cin>>x;
x--;
}
sort(v.begin(), v.end(), [](int a, int b){ return h1[a] < h1[b];});
int ind = -1;
if(v.size() > 1)
ert[v[0]]++;
for(int j = 1; j < (int)v.size(); j++){
int x = get_lca(v[j-1], v[j]);
if(ind == -1 || h1[x] < h1[ind])
ind = x;
ert[x]--;
ert[v[j]]++;
}
if(ind != -1)
ert[ind]--;
}
volt.assign(n, false);
bejar2(0, k, -1);
sort(ki.begin(), ki.end());
cout<<ki.size()<<"\n";
for(int x : ki)
cout<<x<<" ";
cout<<"\n";
return 0;
}
