#include <bits/stdc++.h>
using i64 = long long;
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int n, m, k;
std::cin >> n >> m >> k;
std::vector<std::vector<std::pair<int, int>>> adj(n + 1);
for (int i = 1; i < n; i++) {
int x, y;
std::cin >> x >> y;
adj[x].emplace_back(y, i);
adj[y].emplace_back(x, i);
}
constexpr int K = 20;
std::vector<int> level(n + 1, 0), tin(n + 1, 0), sum(n + 1, 0), ind(n + 1, 0);
std::vector<std::vector<int>> up(K, std::vector<int> (n + 1, 0));
int t = 0;
std::function<void(int, int)> dfs = [&](int u, int p) {
tin[u] = ++t;
up[0][u] = p;
for (int k = 1; k < K; k++) {
up[k][u] = up[k - 1][up[k - 1][u]];
}
level[u] = level[p] + 1;
for (auto [v, w] : adj[u]) {
if (v != p) {
dfs(v, u);
ind[v] = w;
}
}
};
dfs(1, 0);
auto lca = [&] (int x, int y) {
if (level[x] < level[y]) {
std::swap(x, y);
}
for (int k = K - 1; k >= 0; k--) {
if (level[x] - (1 << k) >= level[y]) {
x = up[k][x];
}
}
if (x == y) {
return x;
}
for (int k = K - 1; k >= 0; k--) {
if (up[k][x] != up[k][y]) {
x = up[k][x];
y = up[k][y];
}
}
return up[0][y];
};
auto add = [&] (int x, int y) {
int z = lca(x, y);
sum[x]++;
sum[y]++;
sum[z] -= 2;
};
for (int i = 1; i <= m; i++) {
int s;
std::cin >> s;
std::vector<int> x(s);
for (int j = 0; j < s; j++) {
std::cin >> x[j];
}
std::sort(x.begin(), x.end(), [&] (int x, int y) {
return tin[x] < tin[y];
});
for (int j = 0; j < s; j++) {
add(x[j], x[(j + 1) % s]);
}
};
std::function<void(int, int)> dfs2 = [&] (int u, int p) {
for (auto [v, w] : adj[u]) {
if (v != p) {
dfs2(v, u);
sum[u] += sum[v];
}
}
};
dfs2(1, 0);
std::vector<int> sol;
for (int i = 2; i <= n; i++) {
if (2 * k <= sum[i]) {
sol.emplace_back(ind[i]);
}
}
std::sort(sol.begin(), sol.end());
std::cout << sol.size() << "\n";
for (auto it : sol) {
std::cout << it << " ";
}
return 0;
}
