#include <bits/stdc++.h>
using namespace std;
#pragma GCC target("popcnt")
#define pii pair<int, int>
vector<vector<pii>> graph;
vector<vector<int>> lift;
vector<int> depth;
vector<bitset<10000>> start;
vector<int> ende;
vector<int> minis;
void dfs(int i, int p, int d)
{
depth[i] = d;
for (pii ele:graph[i])
{
if (ele.first==p) continue;
lift[0][ele.first] = i;
dfs(ele.first, i, d+1);
}
}
int finde(int a, int b)
{
if (depth[a]<depth[b]) swap(a, b);
int diff = depth[a]-depth[b];
for (int i = 17; i >= 0; i--)
{
if (diff < (1<<i)) continue;
diff -= 1<<i;
a = lift[i][a];
}
if (a ==b) return a;
for (int i = 17; i >= 0; i--)
{
if (lift[i][a]==lift[i][b]) continue;
a = lift[i][a];
b = lift[i][b];
}
return lift[0][a];
}
int dfs2(int i, int p)
{
int e = ende[i];
for (pii ele:graph[i])
{
if (ele.first == p) continue;
int f = dfs2(ele.first, i);
minis[ele.second] += start[ele.first].count()-f;
start[i]|=start[ele.first];
e+=f;
}
return e;
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
int n, m, k;
cin >> n >> m >> k;
graph.assign(n, vector<pii>());
lift.assign(18, vector<int>(n, -1));
depth.assign(n, 0);
ende.assign(n, 0);
start.assign(n, 0);
minis.assign(n, 0);
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
a--; b--;
graph[a].push_back({b, i});
graph[b].push_back({a, i});
}
dfs(0, -1, 0);
for (int i = 1; i < 18; i++)
{
for (int j = 0; j < n; j++)
{
int next = lift[i-1][j];
if (next == -1) continue;
lift[i][j] = lift[i-1][next];
}
}
for (int i = 0; i <= m/10000; i++)
{
ende.assign(n, 0);
start.assign(n, 0);
for (int j = 0; j < min(10000, m-(i*10000)); j++)
{
int s;
cin >> s;
int lca =0;
for (int h = 0; h < s; h++)
{
int a;
cin >> a;
a--;
if (h==0) lca = a;
else lca = finde(a, lca);
start[a][j] = 1;
}
ende[lca]++;
}
dfs2(0, -1);
}
vector<int> sol;
for (int i = 0; i < n; i++)
{
if (minis[i]>=k) sol.push_back(i);
}
cout << sol.size() << "\n";
for (int ele:sol) cout << ele << " ";
return 0;
}
