#include "bits/stdc++.h"
using namespace std;
const int MAXN = 100'001, MS = 18;
int n, m, k;
vector<int> adj[MAXN];
int jmp[MS][MAXN];
int tin[MAXN];
int h[MAXN];
int pref[MAXN];
int timer = 0;
map<pair<int, int>, int> ind;
int sol[MAXN];
void dfs1(int v, int p, int hei) {
h[v] = hei;
jmp[0][v] = p;
tin[v] = timer++;
for (auto u : adj[v])
if (u != p)
dfs1(u, v, hei + 1);
}
void dfs2(int v, int p) {
for (auto u : adj[v]) {
if (u == p) continue;
dfs2(u, v);
sol[ind[{min(v, u), max(v, u)}]] = pref[u];
pref[v] += pref[u];
}
}
int lca(int a, int b) {
if (h[a] < h[b]) swap(a, b);
int diff = h[a] - h[b];
for (int i = MS - 1; i >= 0; i--)
if (diff & (1 << i))
a = jmp[i][a];
if (a != b) {
for (int i = MS - 1; i >= 0; i--) {
if (jmp[i][a] != jmp[i][b]) {
a = jmp[i][a];
b = jmp[i][b];
}
}
a = jmp[0][a];
}
return a;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 0; i < n - 1; i++) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
ind[{min(a, b), max(a, b)}] = i;
}
dfs1(1, 0, 0);
for (int i = 1; i < MS; i++)
for (int j = 1; j <= n; j++)
jmp[i][j] = jmp[i - 1][jmp[i - 1][j]];
for (int i = 0; i < m; i++) {
int s;
cin >> s;
vector<int> v(s);
for (int j = 0; j < s; j++)
cin >> v[j];
sort(begin(v), end(v), [&](int a, int b) { return tin[a] < tin[b]; });
v.push_back(v[0]);
for (int j = 0; j < s; j++) {
int l = lca(v[j], v[j + 1]);
pref[v[j]]++;
pref[v[j + 1]]++;
pref[l] -= 2;
}
}
dfs2(1, 0);
vector<int> ans;
for (int i = 0; i < n - 1; i++)
if (sol[i] >= 2 * k)
ans.push_back(i + 1);
cout << size(ans) << '\n';
for (int i = 0; i < size(ans); i++)
cout << ans[i] << " \n"[i + 1 == size(ans)];
}
