#include <bits/stdc++.h>
using namespace std;
class Tree {
public:
int n;
vector<vector<int>> adj;
vector<vector<int>> up;
vector<int> dep;
vector<int> tin;
vector<int> tout;
Tree(int n) : n(n) {
adj.resize(n);
up.resize(n);
dep.resize(n);
tin.resize(n);
tout.resize(n);
}
void add_edge(int x, int y) {
adj[x].push_back(y);
adj[y].push_back(x);
}
void dfs(int x, int p) {
static int T = 0;
tin[x] = T++;
up[x].resize(20);
up[x][0] = p;
for (int i = 1; i < 20; ++i) {
up[x][i] = up[up[x][i - 1]][i - 1];
}
for (int y : adj[x]) {
if (y != p) {
dep[y] = dep[x] + 1;
dfs(y, x);
}
}
tout[x] = T;
}
void work() {
dfs(0, 0);
}
void jump(int& at, int k) {
for (int i = 0; i < 20; ++i) {
if (k >> i & 1) {
at = up[at][i];
}
}
}
int lca(int x, int y) {
if (dep[x] < dep[y]) {
swap(x, y);
}
jump(x, dep[x] - dep[y]);
if (x == y) {
return x;
}
for (int i = 20 - 1; i >= 0; --i) {
int new_x = up[x][i];
int new_y = up[y][i];
if (new_x != new_y) {
x = new_x;
y = new_y;
}
}
return up[x][0];
}
bool anc(int x, int y) {
return tin[x] <= tin[y] && tout[y] <= tout[x];
}
};
int main() {
int n, m, k;
cin >> n >> m >> k;
Tree t(n);
vector<pair<int, int>> e;
for (int i = 0; i < n - 1; ++i) {
int a, b;
cin >> a >> b;
--a, --b;
t.add_edge(a, b);
e.emplace_back(a, b);
}
t.work();
vector<int> id(n);
for (int i = 0; i < n - 1; ++i) {
auto [x, y] = e[i];
if (t.dep[x] > t.dep[y]) {
swap(x, y);
}
id[y] = i;
}
vector<int> val(n);
while (m--) {
int s;
cin >> s;
vector<int> a(s);
for (int i = 0; i < s; ++i) {
cin >> a[i];
--a[i];
}
sort(a.begin(), a.end(), [&](int x, int y) {
return t.tin[x] < t.tin[y];
});
for (int i = 1; i < s; ++i) {
a.push_back(t.lca(a[i - 1], a[i]));
}
sort(a.begin(), a.end(), [&](int x, int y) {
return t.tin[x] < t.tin[y];
});
a.resize(unique(a.begin(), a.end()) - a.begin());
for (int i = 1; i < a.size(); ++i) {
val[t.lca(a[i - 1], a[i])] -= 1;
val[a[i]] += 1;
}
}
auto dfs = [&](auto self, int x, int p) -> void {
for (int y : t.adj[x]) {
if (y != p) {
self(self, y, x);
val[x] += val[y];
}
}
};
dfs(dfs, 0, -1);
vector<int> ans;
for (int x = 0; x < n; ++x) {
if (val[x] >= k) {
ans.push_back(id[x]);
}
}
cout << ans.size() << endl;
for (int x : ans) {
cout << x + 1 << " ";
}
}
