#include <bits/stdc++.h>
using namespace std;
//#define DEBUG
void setIO(const string &name) {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin.exceptions(istream::failbit);
#ifdef LOCAL
freopen((name + ".in").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
freopen((name + ".out").c_str(), "w", stderr);
#endif
}
const int inf = 0x3f3f3f3f, mod = 1e9 + 7, maxn = 1e5 + 5, maxs = 20;
vector<pair<int, int>> adj[maxn];
int up[maxn][maxs], depth[maxn], n, tin[maxn];
vector<int> order;
int jmp(int x, int d) {
for (int i = 0; i < maxs; i++) {
if ((d >> i) & 1) {
x = up[x][i];
}
}
return x;
}
int lca(int x, int y) {
if (depth[x] < depth[y]) {
swap(x, y);
}
x = jmp(x, depth[x] - depth[y]);
if (x == y) {
return x;
}
for (int i = maxs - 1; i >= 0; --i) {
int new_x = up[x][i], new_y = up[y][i];
if (new_x != new_y) {
x = new_x, y = new_y;
}
}
return up[x][0];
}
int dist(int x, int y) {
int l = lca(x, y);
return depth[x] - depth[l] + depth[y] - depth[l];
}
void dfs(int c = 0, int p = -1, int d = 0) {
up[c][0] = p;
depth[c] = d;
order.push_back(c);
for (auto &i : adj[c]) {
if (i.first != p) {
dfs(i.first, c, d + 1);
}
}
}
void build() {
for (int i = 1; i < maxs; ++i) {
for (int j = 0; j < n; ++j) {
if (up[j][i - 1] == -1) {
up[j][i] = -1;
} else {
up[j][i] = up[up[j][i - 1]][i - 1];
}
}
}
}
vector<int> sol;
int k;
unordered_map<int, int> diff[maxn];
int cnt[maxn];
void dfs2(int c, int p, int path) {
for (auto &i : diff[c]) {
if (i.second > 0) {
++cnt[c];
}
}
for (auto &i : adj[c]) {
if (i.first != p) {
dfs2(i.first, c, i.second);
if (diff[i.first].size() > diff[c].size()) {
swap(diff[i.first], diff[c]);
swap(cnt[i.first], cnt[c]);
}
for (auto &j : diff[i.first]) {
diff[c][j.first] += j.second;
int cur = diff[c][j.first];
if (cur <= j.second && cur > 0) {
++cnt[c];
} else if (cur <= 0 && cur - j.second > 0) {
--cnt[c];
}
}
diff[i.first].clear();
}
}
if (cnt[c] >= k) {
sol.push_back(path + 1);
}
}
int main() {
setIO("1");
int m;
cin >> n >> m >> k;
for (int i = 0; i < n - 1; ++i) {
int a, b;
cin >> a >> b;
--a, --b;
adj[a].emplace_back(b, i);
adj[b].emplace_back(a, i);
}
dfs();
build();
for (int i = 0; i < m; ++i) {
int s;
cin >> s;
vector<int> a(s);
for (int j = 0; j < s; ++j) {
cin >> a[j];
--a[j];
}
int l = a[0];
for (int j = 0; j < s; ++j) {
++diff[a[j]][i];
l = lca(l, a[j]);
}
diff[l][i] -= s;
}
dfs2(0, -1, -1);
sort(sol.begin(), sol.end());
cout << sol.size() << "\n";
for (auto &i : sol) {
cout << i << " ";
}
cout << "\n";
return 0;
}
