#include <bits/stdc++.h>
using namespace std;
int main()
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
vector<vector<pair<int, int>>> adj(n + 1);
for (int i = 1; i < n; i++)
{
int x, y;
cin >> x >> y;
adj[x].push_back({y, i});
adj[y].push_back({x, i});
}
int K = 20;
vector<int> level(n + 1, 0), tin(n + 1, 0), sum(n + 1, 0), ind(n + 1, 0);
vector<vector<int>> up(K, vector<int> (n + 1, 0));
int t = 0;
function<void(int, int)> dfs = [&](int u, int p)
{
tin[u] = ++t;
up[0][u] = p;
for (int k = 1; k < K; k++)
up[k][u] = up[k - 1][up[k - 1][u]];
level[u] = level[p] + 1;
for (auto [v, w] : adj[u])
if (v != p)
{
dfs(v, u);
ind[v] = w;
}
};
dfs(1, 0);
auto lca = [&] (int x, int y)
{
if(level[x] < level[y])
swap(x, y);
for(int k = K - 1; k >= 0; k--)
if (level[x] - (1 << k) >= level[y])
x = up[k][x];
if (x == y)
return x;
for (int k = K - 1; k >= 0; k--)
if (up[k][x] != up[k][y])
{
x = up[k][x];
y = up[k][y];
}
return up[0][y];
};
auto add = [&] (int x, int y)
{
int z = lca(x, y);
sum[x]++;
sum[y]++;
sum[z] -= 2;
};
for (int i = 1; i <= m; i++)
{
int s;
cin >> s;
vector<int> x(s);
for (int j = 0; j < s; j++)
cin >> x[j];
sort(x.begin(), x.end(), [&](int x, int y){return tin[x] < tin[y];});
for (int j = 0; j < s; j++)
add(x[j], x[(j + 1) % s]);
};
function<void(int, int)> dfs2 = [&] (int u, int p)
{
for (auto [v, w] : adj[u])
if (v != p)
{
dfs2(v, u);
sum[u] += sum[v];
}
};
dfs2(1, 0);
vector<int> sol;
for (int i = 2; i <= n; i++)
if (2 * k <= sum[i])
sol.push_back(ind[i]);
sort(sol.begin(), sol.end());
cout << sol.size() << "\n";
for (auto it : sol)
cout << it << " ";
}
