#include <bits/stdc++.h>
#define int long long
using namespace std;
const int MAXN = 1e5;
const int MAXP = 18;
int par[MAXP][MAXN];
int parEdge[MAXN];
int nbMarque[MAXN];
vector<pair<int, int>> adj[MAXN];
int delta[MAXN];
int depth[MAXN];
int t;
int tin[MAXN];
int nbSommets, nbDeputes, nbVoulu;
void dfs(int iNoeud, int iPere)
{
par[0][iNoeud] = iPere;
tin[iNoeud] = t++;
for (auto [iFrere, iArete] : adj[iNoeud])
if (iFrere != iPere)
{
parEdge[iFrere] = iArete;
depth[iFrere] = depth[iNoeud] + 1;
dfs(iFrere, iNoeud);
}
}
void init()
{
for (int p = 0; p < MAXP-1; ++p)
for (int iSommet = 0; iSommet < nbSommets; ++iSommet)
par[p+1][iSommet] = par[p][par[p][iSommet]];
}
int calcLca(int a, int b)
{
if (depth[a] < depth[b]) swap(a, b);
int diff = depth[a] - depth[b];
for (int p = 0; p < MAXP; ++p)
if ((1<<p) & diff)
a = par[p][a];
if(a == b) return a;
for (int p(MAXP-1); p >= 0; --p)
if (par[p][a] != par[p][b])
a = par[p][a], b = par[p][b];
return par[0][a];
}
int dfs2(int iNoeud)
{
for (auto [iFrere, iArete] : adj[iNoeud])
if (iFrere != par[0][iNoeud])
delta[iNoeud] += dfs2(iFrere);
if (iNoeud)
nbMarque[parEdge[iNoeud]] += delta[iNoeud];
return delta[iNoeud];
}
signed main(void)
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
cin >> nbSommets >> nbDeputes >> nbVoulu;
for (int iArete(0); iArete < nbSommets-1; ++iArete)
{
int u, v;
cin >> u >> v;
--u, --v;
adj[u].emplace_back(v, iArete);
adj[v].emplace_back(u, iArete);
}
dfs(0, 0);
init();
for (int iDepute = 0; iDepute < nbDeputes; ++iDepute)
{
int nbVilles;
cin>> nbVilles;
vector<int> villes(nbVilles);
for (auto &v : villes) {cin >> v; --v;};
sort(villes.begin(), villes.end(), [&](int i, int j) {return tin[i] < tin[j];});
villes.push_back(villes[0]);
for (int i(0); i < nbVilles; ++i)
{
int lca = calcLca(villes[i], villes[i+1]);
delta[villes[i]]++; delta[villes[i+1]]++;
delta[lca]-=2;
}
}
assert(!dfs2(0));
vector<int> sol;
for (int iArete(0); iArete < nbSommets-1; ++iArete)
if (nbMarque[iArete] >= 2*nbVoulu)
sol.push_back(iArete);
cout << sol.size() << endl;
for (auto iArete : sol)
cout << iArete + 1 << ' ';
cout<< endl;
}
