#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
using namespace std;
const int N = 1e5 + 5;
vector <int> ans;
vector <pair <int, int>> adj[N];
int anc[20][N];
int id[N];
int bit[N];
int tin[N];
int tout[N];
int n,k,q,cntdfs;
void update(int pos, int val)
{
for (; pos <= n; pos += pos & -pos)
bit[pos] += val;
}
int getsum(int l, int r)
{
int res = 0;
for (; r > 0; r -= r & -r)
res += bit[r];
for (l--; l > 0; l -= l & -l)
res -= bit[l];
return res;
}
bool isanc(int p, int u)
{
return tin[p] <= tin[u] && tout[u] <= tout[p];
}
int getlca(int u, int v)
{
if (isanc(u, v))
return u;
for (int i = 19; i >= 0; i--)
if (anc[i][u] > 0 && !isanc(anc[i][u], v))
u = anc[i][u];
return anc[0][u];
}
void dfs(int u, int p)
{
anc[0][u] = p;
for (int i = 1; i < 20; i++)
{
int par = anc[i - 1][u];
anc[i][u] = (par < 0) ? -1 : anc[i - 1][par];
}
tin[u] = ++cntdfs;
for (pair <int, int> to : adj[u])
{
int v = to.fi;
if (v == p)
continue;
id[v] = to.se;
dfs(v, u);
}
tout[u] = cntdfs;
}
void query(int u, int v)
{
int p = getlca(u, v);
update(tin[u], 1);
update(tin[v], 1);
update(tin[p], -2);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
//freopen("file.inp","r",stdin);
cin >> n >> q >> k;
for (int i = 1; i < n; i++)
{
int u,v;
cin >> u >> v;
adj[u].push_back(mp(v, i));
adj[v].push_back(mp(u, i));
}
dfs(1, -1);
for (int i = 1; i <= q; i++)
{
int m;
cin >> m;
vector <int> a(m);
for (int &x : a)
cin >> x;
sort(a.begin(), a.end(), [](int i, int j) {return tin[i] < tin[j];});
for (int i = 0; i < m; i++)
query(a[i], a[(i + 1) % m]);
}
for (int i = 2; i <= n; i++)
if (getsum(tin[i], tout[i]) >= 2 * k)
ans.push_back(id[i]);
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (int x : ans)
cout << x << " ";
return 0;
}
