#include <bits/stdc++.h>
using namespace std;
vector<vector<pair<unsigned, unsigned>>> g;
vector<vector<unsigned>> jmp;
vector<unsigned> height, pre, ans;
vector<int> val;
unsigned lift(unsigned u, unsigned h)
{
unsigned z = 0;
while (h)
{
if (h & 1)
u = jmp[u][z];
h >>= 1;
z++;
}
return u;
}
unsigned lca(unsigned u, unsigned v)
{
if (height[u] < height[v])
swap(u, v);
u = lift(u, height[u] - height[v]);
if (u == v)
return u;
for (size_t i = jmp[u].size() - 1; i < jmp[u].size(); i--)
if (jmp[u][i] != jmp[v][i])
u = jmp[u][i], v = jmp[v][i];
return jmp[u][0];
}
unsigned traverse(
vector<unsigned> &path, unsigned u, unsigned p, unsigned h, unsigned i)
{
for (unsigned i = 1; i <= path.size(); i <<= 1)
jmp[u].push_back(path[path.size() - i]);
height[u] = h;
path.push_back(u);
pre[u] = i++;
for (auto const &[v, j] : g[u])
if (v != p)
i = traverse(path, v, u, h + 1, i);
path.pop_back();
return i;
}
void calc_ans(unsigned u, unsigned p)
{
for (auto const &[v, j] : g[u])
{
if (v != p)
{
calc_ans(v, u);
ans[j] = val[v];
val[u] += val[v];
}
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
size_t n, m, k;
cin >> n >> m >> k;
g = vector<vector<pair<unsigned, unsigned>>>(n);
jmp = vector<vector<unsigned>>(n);
height = vector<unsigned>(n);
pre = vector<unsigned>(n);
ans = vector<unsigned>(n - 1);
val = vector<int>(n, 0);
for (size_t i = 0; i < n - 1; i++)
{
unsigned u, v;
cin >> u >> v;
g[u - 1].emplace_back(v - 1, i);
g[v - 1].emplace_back(u - 1, i);
}
vector<unsigned> path;
assert(traverse(path, 0, -1, 0, 0) == n);
for (size_t i = 0; i < m; i++)
{
size_t s;
cin >> s;
vector<pair<unsigned, unsigned>> y(s);
for (auto &[j, u] : y)
{
cin >> u;
u--;
j = pre[u];
}
sort(y.begin(), y.end());
y.resize(unique(y.begin(), y.end()) - y.begin());
for (size_t j = 0; j < y.size(); j++)
{
val[y[j].second]++;
val[y[(j + 1) % y.size()].second]++;
val[lca(y[j].second, y[(j + 1) % y.size()].second)] -= 2;
}
}
calc_ans(0, -1);
unsigned c = 0;
for (unsigned const &x : ans)
c += (x >= 2 * k);
cout << c << '\n';
for (size_t i = 0; i < n - 1; i++)
if (ans[i] >= 2 * k)
cout << i + 1 << ' ';
cout << '\n';
}
