#include <iostream>
#include <cmath>
#include <algorithm>
#include <vector>
#include <array>
#include <set>
#include <queue>
#include <map>
#include <iomanip>
#include <stack>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string>
#include <fstream>
#include <unordered_map>
using namespace std;
using ll = long long;
using ld = long double;
using Mat = array<array<ll, 2>, 2>;
const ll mod1 = 1e9 + 7;
const ll mod2 = 1e9 + 123;
const int MAXN = 1e6 + 11;
const ll P = 31;
int n, m, k;
vector<pair<int,int>> adj[MAXN];
set<int> curr[MAXN];
int ans[MAXN];
vector<int> to_del[MAXN];
int tin[MAXN];
int timer;
int tout[MAXN];
int up[MAXN][30];
int papa[MAXN];
void dfs(int v, int p)
{
tin[v] = ++timer;
up[v][0] = p;
for (int i = 1; i <= 29; ++i)
up[v][i] = up[up[v][i - 1]][i - 1];
for (auto u : adj[v]) {
if (u.first != p)
{
dfs(u.first, v);
papa[u.first] = u.second;
}
}
tout[v] = ++timer;
}
bool is_ancestor(int u, int v)
{
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v)
{
if (is_ancestor(u, v))
return u;
if (is_ancestor(v, u))
return v;
for (int i = 29; i >= 0; --i) {
if (!is_ancestor(up[u][i], v))
u = up[u][i];
}
return up[u][0];
}
set<int> merge(set<int> a, set<int> b)
{
if (a.size() > b.size())
swap(a, b);
for (auto x : a)
b.insert(x);
a.clear();
return b;
}
void dfs2(int v, int p)
{
for (auto u : adj[v])
{
if (u.first == p)
continue;
dfs2(u.first, v);
curr[v] = merge(curr[v], curr[u.first]);
}
for(auto D : to_del[v])
if (curr[v].find(D) != curr[v].end())
curr[v].erase(D);
//cout << " NOW NODE: " << v << '\n';
//for (auto x : curr[v])
//cout << x << " ";
//cout << '\n';
ans[papa[v]] = curr[v].size();
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
//freopen("runaway.in", "r", stdin);
//freopen("runaway.out", "w", stdout);
cin >> n >> m >> k;
for (int i = 1; i < n; i++)
{
int a, b;
cin >> a >> b;
adj[a].push_back({ b ,i});
adj[b].push_back({ a ,i});
}
dfs(1, 1);
for (int i = 1; i <= m; i++)
{
int s;
cin >> s;
int lc;
vector<int> arr;
for (int j = 0; j < s; j++)
{
int v;
cin >> v;
arr.push_back(v);
curr[v].insert(i);
}
lc = lca(arr[0], arr[1]);
for (int i = 2; i < arr.size(); i++)
lc = lca(lc, arr[i]);
to_del[lc].push_back(i);
//cout << "LCA " << lc << '\n';
}
dfs2(1, 1);
vector<int> fin;
for (int i = 1; i < n; i++)
if (ans[i] >= k)
fin.push_back(i);
cout << fin.size() << '\n';
for (auto x : fin)
cout << x << " ";
return 0;
}
