#include <bits/stdc++.h>
#define pb push_back
#define fi first
#define se second
using namespace std;
int log_n = 20;
vector<int> depth, idx;
vector<pair<int, int>> edges;
vector<vector<pair<int, int>>> adj;
vector<vector<int>> parent;
struct Segtree {
int n;
vector<int> st, lz;
Segtree(int n) : n(n), st(vector<int>(4*n, 0)), lz(vector<int>(4*n, 0)) {};
void change(int p, int l, int r, int i, int v) {
if (l == r) st[p] += v;
else {
int m = (l+r)/2;
if (i <= m) change(2*p, l, m, i, v);
else change(2*p+1, m+1, r, i, v);
st[p] = st[2*p]+st[2*p+1];
}
}
int sum(int p, int l, int r, int i, int j) {
if (i > j) return 0;
if (i == l && j == r) return st[p];
int m = (l+r)/2;
return sum(2*p, l, m, i, min(m, j))+sum(2*p+1, m+1, r, max(i, m+1), j);
}
void change(int i, int v) { change(1, 0, n-1, i, v); }
int sum(int i, int j) { return sum(1, 0, n-1, i, j); }
};
int jump(int u, int k) {
for (int i = 0; i < log_n; ++i) {
if (k&(1<<i)) u = parent[u][i];
}
return u;
}
int LCA(int a, int b) {
if (depth[a] > depth[b]) swap(a, b);
b = jump(b, depth[b]-depth[a]);
if (a == b) return a;
for (int i = log_n-1; i >= 0; --i) {
if (parent[a][i] != parent[b][i]) {
a = parent[a][i];
b = parent[b][i];
}
}
return parent[b][0];
}
int cnt = 0;
void dfs(int u, int p) {
edges[u].fi = cnt;
parent[u][0] = p;
depth[u] = depth[p]+1;
for (int i = 1; i < log_n; ++i) {
parent[u][i] = parent[parent[u][i-1]][i-1];
}
for (pair<int, int> v: adj[u]) {
if (v.fi == p) continue;
++cnt;
dfs(v.fi, u);
idx[v.fi] = v.se;
}
edges[u].se = cnt;
}
void solve(int n, int m, int k) {
Segtree St(n);
while (m--) {
int s; cin >> s;
vector<pair<int, int>> nodes(s);
for (int i = 0; i < s; ++i) {
cin >> nodes[i].se;
nodes[i].se--;
nodes[i].fi = edges[nodes[i].se].fi;
}
sort(nodes.begin(), nodes.end());
for (int i = 1; i <= s; ++i) {
int lca = LCA(nodes[i%s].se, nodes[i-1].se);
St.change(edges[nodes[i%s].se].fi, 1);
St.change(edges[nodes[i-1].se].fi, 1);
St.change(edges[lca].fi, -2);
}
}
vector<int> ans;
for (int i = 0; i < n-1; ++i) {
if (St.sum(edges[i].fi, edges[i].se) >= 2*k) ans.pb(idx[i]);
}
sort(ans.begin(), ans.end());
cout << (int)ans.size() << endl;
for (int i: ans) cout << i << " ";
cout << endl;
}
int main() {
int n, m, k;
cin >> n >> m >> k;
depth = idx = vector<int>(n, -1);
adj = vector<vector<pair<int, int>>>(n);
parent = vector<vector<int>>(n, vector<int>(log_n));
edges = vector<pair<int, int>>(n);
for (int i = 0; i < n-1; ++i) {
int a, b;
cin >> a >> b;
--a; --b;
adj[a].pb({b, i+1});
adj[b].pb({a, i+1});
}
dfs(0, 0);
solve(n, m, k);
return 0;
}
