#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 10;
const int MAXLOG = 17 + 1;
int n, m, k;
vector<vector<pair<int, int>>> tree(MAXN);
int parEdge[MAXN]; // idx of the edge (par[x], x)
int lift[MAXN][MAXLOG];
int in[MAXN], out[MAXN], timer = 0;
int dp[MAXN];
void dfs1(int node, int par)
{
in[node] = ++timer;
lift[node][0] = par;
for(int i = 1 ; i < MAXLOG ; ++i)
{
int prev = lift[node][i - 1];
lift[node][i] = lift[prev][i - 1];
}
for(const auto& [child, idx] : tree[node])
{
if(child == par) continue;
parEdge[child] = idx;
dfs1(child, node);
}
out[node] = timer;
}
bool is_ancestor(int a, int b)
{
return (in[a] <= in[b] && out[a] >= out[b]);
}
int lca(int a, int b)
{
if(is_ancestor(a, b)) return a;
if(is_ancestor(b, a)) return b;
for(int i = MAXLOG - 1 ; i >= 0 ; --i)
{
int up = lift[a][i];
if(up != 0 && !is_ancestor(up, b))
{
a = up;
}
}
return lift[a][0];
}
void update(int a, int b)
{
++dp[a]; ++dp[b];
dp[lca(a, b)] -= 2;
}
void dfs2(int node, int par)
{
for(const auto& [child, idx] : tree[node])
{
if(child == par) continue;
dfs2(child, node);
dp[node] += dp[child];
}
}
void solve()
{
cin >> n >> m >> k;
for(int i = 1 ; i <= n - 1 ; ++i)
{
int a, b; cin >> a >> b;
tree[a].push_back({b, i});
tree[b].push_back({a, i});
}
dfs1(1, 0);
for(int i = 1 ; i <= m ; ++i)
{
int s;
cin >> s;
vector<int> cities(s, 0);
for(int j = 0 ; j < s ; ++j)
{
cin >> cities[j];
}
sort(cities.begin(), cities.end(), [&](int u, int v)
{
return in[u] < in[v];
});
for (int j = 0; j < s; ++j)
{
int a = cities[j], b = cities[(j + 1) % s];
update(a, b);
}
}
dfs2(1, 0);
vector<int> answer;
for(int i = 2 ; i <= n ; ++i)
{
if(dp[i] >= 2 * k)
{
answer.push_back(parEdge[i]);
}
}
sort(answer.begin(), answer.end());
cout << answer.size() << "\n";
for(int a : answer) cout << a << " ";
cout << "\n";
}
void fastIO()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
int main()
{
fastIO();
solve();
return 0;
}
