#include <cstdio>
#include <iostream>
#include <vector>
#include <list>
#include <string>
#include <set>
#include <map>
#include <algorithm>
#include <fstream>
#include <cmath>
#include <queue>
#include <stack>
#include <cassert>
#include <cstring>
#include <climits>
#include <functional>
#include <cstdlib>
#include <complex>
#include <array>
#include <iomanip>
#include <bitset>
#include <unordered_map>
#include <random>
#define fileIO(name) if(fopen(name".in", "r")) {freopen(name".in", "r", stdin); freopen(name".out", "w", stdout);}
using namespace std;
const int MAXN = 4e5 + 111;
using ll = long long;
const int P = 31;
const ll mod1 = 1e9 + 7;
const ll mod2 = 998244353;
using ld = long double;
const ld EPS = 1e-5;
using pii = pair<int, int>;
typedef complex<ll> Point;
const int K = 600;
int n, m, k;
vector<pair<int,int>> adj[MAXN];
int up[MAXN][20];
int tin[MAXN];
int tout[MAXN];
vector<pair<int, int>> edges;
int timer;
vector<int> add[MAXN];
vector<int> rem[MAXN];
vector<int> answer;
void dfs(int v, int p)
{
tin[v] = ++timer;
up[v][0] = p;
for (int i = 1; i < 20; i++)
up[v][i] = up[up[v][i - 1]][i - 1];
for (auto u : adj[v])
{
if (u.first == p)
continue;
dfs(u.first, v);
}
tout[v] = ++timer;
}
bool is_ancestor(int u, int v)
{
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int a, int b)
{
if (is_ancestor(a, b))
return a;
if (is_ancestor(b, a))
return b;
for (int i = 19; i >= 0; i--)
{
if (!is_ancestor(up[a][i], b))
a = up[a][i];
}
return up[a][0];
}
set<int> vals[MAXN];
void check(int v, int p)
{
int big = v;
for (auto u : adj[v])
{
if (u.first == p)
continue;
check(u.first, v);
if (vals[u.first].size() > vals[big].size())
big = u.first;
if (vals[u.first].size() >= k)
answer.push_back(u.second);
}
swap(vals[v], vals[big]);
for (auto x : adj[v])
{
if (x.first == p)
continue;
for (auto vv : vals[x.first])
vals[v].insert(vv);
}
for (auto x : add[v])
vals[v].insert(x);
for (auto x : rem[v])
vals[v].erase(x);
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//fileIO("cardgame");
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});
edges.push_back({ a,b });
}
dfs(1, 1);
for (int i = 0; i < m; i++)
{
int s;
cin >> s;
int y = 0;
vector<int> vertices;
for (int j = 0; j < s; j++)
{
int x;
cin >> x;
vertices.push_back(x);
y = (y == 0 ? x : lca(y, x));
}
rem[y].push_back(i + 1);
for (int j = 0; j < s; j++)
add[vertices[j]].push_back(i + 1);
}
check(1, 1);
cout << answer.size() << '\n';
for (auto x : answer)
cout << x << " ";
cout << '\n';
return 0;
}
