#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
int n, m, k, a, b;
int head[100000], tail[100000], pre[20][100000], val[100000], q[100000], lca[100000];
vector<pair<int, int>> g[100000];
vector<int> res;
inline void DFS(int node, int par)
{
head[node] = a++;
pre[0][node] = par;
for (int i = 1; i < 20; ++i)
{
pre[i][node] = pre[i - 1][pre[i - 1][node]];
}
for (auto &i : g[node])
{
if (i.first != par)
{
DFS(i.first, node);
}
}
tail[node] = a - 1;
}
inline void DFS1(int node, int par, int last)
{
for (auto & i : g[node])
{
if (i.first != par)
{
DFS1(i.first, node, i.second);
val[node] += val[i.first];
}
}
// cout << node << " " << val[node] << "\n";
if (val[node] >= k)
{
res.push_back(last);
}
}
inline bool comp(const int &ina, const int &inb)
{
return head[a] < head[b];
}
inline bool IsPar(int par, int child)
{
return head[par] <= head[child] && tail[child] <= tail[par];
}
inline int LCA(int ina, int inb)
{
if (IsPar(ina, inb))
{
return ina;
}
for (int i = 19; i >= 0; --i)
{
if (!IsPar(pre[i][ina], inb))
{
ina = pre[i][ina];
}
}
return pre[0][ina];
}
int main()
{
setup();
cin >> n >> m >> k;
for (int i = 0; i < n - 1; ++i)
{
cin >> a >> b;
g[a - 1].push_back({b - 1, i + 1});
g[b - 1].push_back({a - 1, i + 1});
}
a = 0;
DFS(0, 0);
while (m--)
{
cin >> a;
if (a == 0)
{
continue;
}
for (int i = 0; i < a; ++i)
{
cin >> q[i];
val[--q[i]]++;
}
sort(q, q + a, comp);
lca[0] = pre[0][q[0]];
val[lca[0]]--;
for (int i = 1; i < a; ++i)
{
lca[i] = LCA(q[i - 1], q[i]);
val[lca[i]] -= 2;
val[lca[i - 1]] += 1;
}
}
DFS1(0, 0, 0);
sort(res.begin(), res.end());
cout << res.size() << "\n";
for (auto & i : res)
{
cout << i << " ";
}
return 0;
}
