#include <bits/stdc++.h>
using namespace std;
constexpr size_t N = 100000;
size_t n, m, k, ans[N], l;
vector<pair<int, int>> g[N];
vector<int> anc[N];
int x[N], h[N], r[N], preorder[N];
int trav(int u, int p, vector<int> &path, int j = 0)
{
preorder[u] = j++;
h[u] = path.size();
for (size_t i = 1; i <= path.size(); i <<= 1)
anc[u].push_back(path[path.size() - i]);
path.push_back(u);
for (auto const &[v, _] : g[u])
if (v != p)
j = trav(v, u, path, j);
path.pop_back();
return j;
}
int lift(int u, int y)
{
int z = 0;
while (y)
{
if (y & 1)
u = anc[u][z];
y >>= 1;
++z;
}
return u;
}
int lca(int u, int v)
{
if (h[u] < h[v])
u ^= v, v ^= u, u ^= v;
u = lift(u, h[u] - h[v]);
if (u == v)
return u;
for (size_t i = anc[u].size() - 1; i < anc[u].size(); --i)
if (anc[u][i] != anc[v][i])
u = anc[u][i], v = anc[v][i];
return anc[u][0];
}
void sum(int u, int p)
{
for (auto const &[v, i] : g[u])
if (v != p)
sum(v, u), x[u] += x[v], ans[i] = x[v], l += x[v] >= 2 * k;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
for (size_t i = 0; i < n - 1; ++i)
{
int u, v;
cin >> u >> v;
g[u - 1].emplace_back(v - 1, i);
g[v - 1].emplace_back(u - 1, i);
}
vector<int> path;
trav(0, -1, path);
for (size_t i = 0; i < m; ++i)
{
int s;
cin >> s;
for (size_t j = 0; j < s; ++j)
cin >> r[j], --r[j];
sort(r, r + s, [](int const &u, int const &v)
{ return preorder[u] < preorder[v]; });
r[s] = r[0];
for (size_t j = 0; j < s; ++j)
++x[r[j]], ++x[r[j + 1]], x[lca(r[j], r[j + 1])] -= 2;
}
sum(0, -1);
cout << l << '\n';
for (size_t i = 0; i < n - 1; ++i)
if (ans[i] >= 2 * k)
cout << i + 1 << ' ';
cout << '\n';
}
