#include <bits/stdc++.h>
using namespace std;
#define pii pair <int, int>
#define fi first
#define se second
const int maxn = 1e5 + 5;
int n, m, k, id[maxn], timer;
vector <int> adj[maxn], ans;
int dep[maxn], up[maxn][20], delta[maxn];
int in[maxn], out[maxn];
pii edges[maxn];
void dfs(int u, int p) {
up[u][0] = p;
for (int i = 1; i < 20; i++)
up[u][i] = up[ up[u][i-1] ][i-1];
in[u] = ++timer;
for (int v : adj[u]) {
if (v == p) continue;
dep[v] = dep[u] + 1;
dfs(v, u);
}
out[u] = timer;
}
int lca(int u, int v) {
if (dep[u] < dep[v]) swap(u, v);
int diff = dep[u] - dep[v];
for (int i = 0; i < 20; i++) if (diff >> i & 1) u = up[u][i];
if (u == v) return u;
for (int i = 19; i >= 0; i--) if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
return up[u][0];
}
int dfs2(int u, int p) {
for (int v : adj[u]) if (v != p) {
int t = dfs2(v, u);
if (t >= k) ans.push_back(id[v]);
delta[u] += t;
}
return delta[u];
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> m >> k;
for (int i = 1, u, v; i < n; i++) {
cin >> u >> v;
adj[u].push_back(v);
adj[v].push_back(u);
edges[i] = {u, v};
}
dep[1] = 0;
dfs(1, 0);
for (int i = 1; i < n; i++) {
int u = edges[i].fi, v = edges[i].se;
if (dep[u] > dep[v]) id[u] = i;
else id[v] = i;
}
for (int i = 0, x; i < m; i++) {
cin >> x;
vector<int> vc(x);
for (int j = 0; j < x; j++) cin >> vc[j];
sort(vc.begin(), vc.end(), [&](int a, int b){ return in[a] < in[b]; });
for (int j = 1; j < x; j++) {
int u = vc[j-1], v = vc[j];
int w = lca(u, v);
delta[u]++;
delta[v]++;
delta[w] -= 2;
}
}
dfs2(1, 0);
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (int i : ans) cout << i << ' ';
return 0;
}
