#include <bits/stdc++.h>
using namespace std;
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
int N, M, K;
cin >> N >> M >> K;
vector<vector<int>> adj(N);
map<pair<int, int>, int> edge_id;
for (int i = 1; i < N; i++) {
int u, v;
cin >> u >> v;
u--, v--;
edge_id[{u, v}] = i;
edge_id[{v, u}] = i;
adj[u].emplace_back(v);
adj[v].emplace_back(u);
}
vector<int> st(N);
vector<int> siz(N);
vector<int> par(N);
vector<int> root(N);
vector<int> depth(N);
const auto DfsInit = [&](const auto &self, int u, int p) -> void {
if (p != -1) {
adj[u].erase(find(begin(adj[u]), end(adj[u]), p));
}
par[u] = p;
siz[u] = 1;
for (auto &v : adj[u]) {
depth[v] = depth[u] + 1;
self(self, v, u);
siz[u] += siz[v];
if (siz[v] > siz[adj[u][0]]) {
swap(v, adj[u][0]);
}
}
};
const auto DfsHld = [&](const auto &self, int u) -> void {
static int timer = 0;
st[u] = timer++;
for (auto v : adj[u]) {
root[v] = v == adj[u][0] ? root[u] : v;
self(self, v);
}
};
DfsInit(DfsInit, 0, -1);
DfsHld(DfsHld, 0);
const auto Lca = [&](int x, int y) {
while (root[x] != root[y]) {
if (depth[root[x]] > depth[root[y]]) swap(x, y);
y = par[root[y]];
}
if (depth[x] > depth[y]) swap(x, y);
return x;
};
vector<int> cnt(N);
vector<int> answer;
const auto DfsCnt = [&](const auto &self, int u) -> void {
for (auto v : adj[u]) {
self(self, v);
if (cnt[v] >= K) {
answer.emplace_back(edge_id[{u, v}]);
}
cnt[u] += cnt[v];
}
};
while (M--) {
int s;
cin >> s;
vector<int> ls;
for (int i = 0; i < s; i++) {
int u;
cin >> u;
ls.emplace_back(--u);
}
sort(begin(ls), end(ls), [&](int i, int j) {
return st[i] < st[j];
});
for (int i = 0; i < s; i++) {
int u = ls[(i + 0) % s];
int v = ls[(i + 1) % s];
cnt[v]++;
cnt[Lca(u, v)]--;
}
}
DfsCnt(DfsCnt, 0);
cout << answer.size() << '\n';
sort(begin(answer), end(answer));
for (int i = 0; i < int(answer.size()); i++) {
cout << answer[i] << " \n"[i + 1 == answer.size()];
}
return 0;
}
