#include <bits/stdc++.h>
#define DEBUG(x) cout << #x << ": " << x << '\n';
using namespace std;
const int MAXN = 1e5 + 1;
const int LOGN = 20;
int depth[MAXN];
int euler[MAXN];
int jmp[LOGN][MAXN];
int starting[MAXN];
int ending[MAXN];
vector<int> adj[MAXN];
int timer = 0;
void init_lca(int n, int p = 0) {
depth[n] =depth[p] + 1;
jmp[0][n] = p;
euler[n] = timer++;
for (int x : adj[n]) {
if (x == p) continue;
init_lca(x, n);
}
}
void init_lca() {
init_lca(1);
for (int i = 1; i < LOGN; ++i) {
for (int j = 1; j < MAXN; ++j) {
jmp[i][j] = jmp[i - 1][jmp[i - 1][j]];
}
}
}
int lca(int a, int b) {
if (depth[a] < depth[b]) swap(a, b);
for (int i = 0; i < LOGN; ++i) {
if ((depth[a] - depth[b]) & (1 << i)) a = jmp[i][a];
}
if (a == b) return a;
for (int i = LOGN - 1; i >= 0; --i) {
int la = jmp[i][a];
int lb = jmp[i][b];
if (la != lb) {
a = la;
b = lb;
}
}
return jmp[0][a];
}
map<pair<int, int>, int> edge_to_idx;
int ans[MAXN];
int solve(int n, int p = -1) {
int k = starting[n];
for (int x : adj[n]) {
if (x == p) continue;
k += solve(x, n);
}
k -= ending[n];
ans[edge_to_idx[{n, p}]] = k;
return k;
}
int main() {
int n, m, k;
cin >> n >> m >> k;
for (int i = 1; i < n; ++i) {
int a, b;
cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
edge_to_idx[{a, b}] = i;
edge_to_idx[{b, a}] = i;
}
init_lca();
for (int i = 0; i < m; ++i) {
int s;
cin >> s;
vector<int> v(s);
for (int i = 0; i < s; ++i) {
cin >> v[i];
}
sort(v.begin(), v.end(), [&](int a, int b) {
return euler[a] < euler[b];
});
int root = v[0];
for (int i = 1; i < s; ++i) {
root = lca(root, v[i]);
}
int last = root;
for (int i = 0; i < s; ++i) {
ending[lca(last, v[i])]++;
starting[v[i]]++;
last = v[i];
}
}
solve(1);
vector<int> v;
for (int i = 1; i < n; ++i) {
if (ans[i] >= k) v.push_back(i);
}
cout << v.size() << '\n';
for (int x : v) {
cout << x << ' ';
}
}
