#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <list>
#include <utility>
#include <cmath>
#include <numeric>
#include <assert.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pb push_back
#define endl "\n"
#define all(x) x.begin(), x.end()
const int M = 200007;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const double pi = acos(-1);
const int dx[] = {1, 0, -1, 0}, dy[] = {0, 1, 0, -1};
vector <int> ans;
vector < pair <int,int> > adj[M];
int n, m, k, anc[M][20], dep[M], in[M], out[M], pref[M], timer, edge[M], c[M];
bool cmp(int a, int b) { return in[a] < in[b]; }
void calc(int node, int p)
{
in[node] = ++timer;
for(auto i : adj[node]) if(i.F != p){
edge[i.F] = i.S;
dep[i.F] = dep[node] + 1;
anc[i.F][0] = node;
calc(i.F, node);
}
out[node] = ++timer;
return;
}
int lca(int x, int y)
{
if(x == y) return x;
if(dep[x] > dep[y]) swap(x, y);
for(int i = 19; i >= 0; --i) if(anc[y][i] && dep[anc[y][i]] >= dep[x]) y = anc[y][i];
if(x == y) return x;
for(int i = 19; i >= 0; --i) if(anc[x][i] && anc[x][i] != anc[y][i]){
x = anc[x][i];
y = anc[y][i];
}
return anc[x][0];
}
void get(int node, int p)
{
for(auto i : adj[node]) if(i.F != p){
get(i.F, node);
pref[node] += pref[i.F];
if(pref[i.F] >= 2 * k) ans.pb(i.S);
}
return;
}
int main()
{
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin >> n >> m >> k;
for(int i = 1; i < n; ++i){
int a, b;
cin >> a >> b;
adj[a].pb({b, i});
adj[b].pb({a, i});
}
calc(1, 0);
for(int j = 1; j < 20; ++j) for(int i = 1; i <= n; ++i) anc[i][j] = anc[anc[i][j - 1]][j - 1];
for(int i = 1; i <= m; ++i){
int s, res = 0;
cin >> s;
for(int j = 1; j <= s; ++j) cin >> c[j];
sort(c + 1, c + s + 1, cmp);
c[s + 1] = c[1];
for(int i = 1; i <= s; ++i){
++pref[c[i]];
++pref[c[i + 1]];
pref[lca(c[i], c[i + 1])] -= 2;
}
}
get(1, 0);
sort(all(ans));
cout << ans.size() << endl;
for(auto i : ans) cout << i << " ";
cout << endl;
return 0;
}
