#include <bits/stdc++.h>
#define ALL(x) begin(x), end(x)
using namespace std;
using i64 = long long;
template <class T>
using vec = vector<T>;
int main() {
cin.tie(nullptr)->sync_with_stdio(false);
int n, q, k; cin >> n >> q >> k;
vec<vec<pair<int, int>>> G(n);
vec<int> parent(n), pa_edge(n), head(n), depth(n), dfn(n), order(n), sum(n + 1);
for (int i = 1; i < n; i++) {
int x, y; cin >> x >> y;
--x, --y;
G[x].emplace_back(y, i);
G[y].emplace_back(x, i);
}
{
vec<int> heavy(n, -1);
auto get_heavy = [&](auto&& f, int x, int pre) -> int {
int ret{1}, heavy_sz{0};
for (auto [to, i] : G[x]) if (to != pre) {
parent[to] = x;
pa_edge[to] = i;
depth[to] = depth[x] + 1;
auto to_sz = f(f, to, x);
ret += to_sz;
if (to_sz > heavy_sz) heavy[x] = to, heavy_sz = to_sz;
}
return ret;
};
get_heavy(get_heavy, 0, -1);
int t = 0;
auto dfs = [&](auto&& f, int x, int pre, int hd) -> void {
head[x] = hd;
dfn[x] = t++;
order[dfn[x]] = x;
if (heavy[x] != -1) f(f, heavy[x], x, hd);
for (auto [to, i] : G[x]) if (to != pre && to != heavy[x])
f(f, to, x, to);
};
dfs(dfs, 0, -1, 0);
}
auto lca = [&](int x, int y) -> int {
while (head[x] != head[y]) {
if (depth[head[x]] < depth[head[y]]) swap(x, y);
x = parent[head[x]];
}
return depth[x] < depth[y] ? x : y;
};
auto get_virtual_tree_edges = [&](vec<int> a) -> vec<pair<int, int>> {
sort(ALL(a), [&](const auto lhs, const auto rhs) { return dfn[lhs] < dfn[rhs]; });
for (int i = 1, sz = (int)size(a); i < sz; i++) {
a.emplace_back(lca(a[i - 1], a[i]));
}
sort(ALL(a), [&](const auto lhs, const auto rhs) { return dfn[lhs] < dfn[rhs]; });
a.resize(unique(ALL(a)) - begin(a));
vec<pair<int, int>> ret(size(a) - 1);
for (int i = 1; i < (int)size(a); i++) ret[i - 1] = {lca(a[i - 1], a[i]), a[i]};
return ret;
};
while (q--) {
int s; cin >> s;
vec<int> a(s);
for (auto& x : a) {
cin >> x;
--x;
}
for (auto [pa, x] : get_virtual_tree_edges(a)) {
while (head[pa] != head[x]) {
if (depth[head[pa]] > depth[head[x]]) swap(pa, x);
++sum[dfn[head[x]]];
--sum[dfn[x] + 1];
x = parent[head[x]];
}
if (depth[pa] > depth[x]) swap(pa, x);
++sum[dfn[pa] + 1];
--sum[dfn[x] + 1];
}
}
inclusive_scan(ALL(sum), begin(sum));
vec<int> ans;
for (int i = 1; i < n; i++) if (sum[i] >= k) ans.emplace_back(pa_edge[order[i]]);
cout << size(ans) << '\n';
for (auto x : ans) cout << x << ' ';
if (!empty(ans)) cout << '\n';
}
