// Krishnaya vaasudevaya
// Devaki nandanayacha
// Nanda gopakumaraya
// Govindaya namoh namaha
// Jay ganeshji, Jay Guruji, Jay Ram-bhakt Hanumanji
#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#define ff first
#define ss second
#define pb emplace_back
#define eb emplace
// Competion only
using namespace std;
using namespace __gnu_pbds;
using ll = long long;
using ull = unsigned ll;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<pii>;
using vll = vector<pll>;
const int inf = 1e9 + 7;
const ll llinf = 1e18 + 7;
constexpr ll mod = 1e9 + 7;
const vector<pii> dirs4 = {{0, -1}, {0, 1}, {-1, 0}, {1, 0}};
const vector<pii> dirs8 = {{-1, -1}, {-1, 0}, {-1, 1}, {0, -1}, {0, 1}, {1, -1}, {1, 0}, {1, 1}};
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
ll fastPow(ll a, ll b)
{
ll res = 1;
while(b) {
if(b & 1)
res *= a;
a *= a, b >>= 1;
}
return res;
}
ll fastPow(ll a, ll b, ll m)
{
ll res = 1;
a %= m;
while(b) {
if(b & 1)
(res *= a) %= m;
(a *= a) %= m, b >>= 1;
}
return res;
}
ll modinv(ll x, ll m)
{
return fastPow(x, m - 2, m);
}
ll moddiv(ll numerator, ll denominator, ll m) {
return numerator * modinv(denominator, m);
}
template<typename T>
inline void maximize(T &trg, T src) {
trg = max(trg, src);
}
template<typename T>
inline void minimize(T &trg, T src) {
trg = min(trg, src);
}
template<typename T>
constexpr ostream &operator<<(ostream &stream, const vector<T> &other) {
stream << '[';
size_t n = other.size();
if(n > 0) {
for(size_t i = 0; i < n - 1; i++)
stream << other[i] << ", ";
stream << other[n - 1];
}
return stream << ']';
}
template<typename T>
constexpr ostream &operator<<(ostream &stream, const set<T> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << *it << ", ", ++it;
stream << *it;
}
return stream << '}';
}
template<typename T>
constexpr ostream &operator<<(ostream &stream, const multiset<T> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << *it << ", ", ++it;
stream << *it;
}
return stream << '}';
}
template<typename T>
constexpr ostream &operator<<(ostream &stream, const ordered_set<T> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << *it << ", ", ++it;
stream << *it;
}
return stream << '}';
}
template<typename T1, typename T2>
constexpr ostream &operator<<(ostream &stream, const map<T1, T2> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << (*it).first << ':' << (*it).second << ", ", ++it;
stream << (*it).first << ':' << (*it).second;
}
return stream << '}';
}
template<typename T1, typename T2>
constexpr ostream &operator<<(ostream &stream, const multimap<T1, T2> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << (*it).first << ':' << (*it).second << ", ", ++it;
stream << (*it).first << ':' << (*it).second;
}
return stream << '}';
}
template<typename T1, typename T2>
constexpr ostream &operator<<(ostream &stream, const unordered_map<T1, T2> &other) {
stream << '{';
size_t n = other.size();
if(n > 0) {
auto it = other.begin();
for(size_t i = 0; i < n-1; i++)
stream << (*it).first << ':' << (*it).second << ", ", ++it;
stream << (*it).first << ':' << (*it).second;
}
return stream << '}';
}
template<typename T1, typename T2>
constexpr ostream &operator<<(ostream &stream, const pair<T1, T2> &other) {
return stream << '(' << other.first << ", " << other.second << ')';
}
template<typename T>
istream &operator>>(istream &stream, vector<T> &other) {
for(auto &e : other)
stream >> e;
return stream;
}
template<typename T1, typename T2>
istream &operator>>(istream &stream, pair<T1, T2> &other) {
stream >> other.first >> other.second;
return stream;
}
template<size_t I = 0, typename ...T>
ostream &operator<<(ostream &stream, const tuple<T...> &other) {
if constexpr(I == 0)
stream << '(';
stream << get<I>(other);
if constexpr(I < sizeof...(T) - 1) {
stream << ", ";
return operator<<<I + 1>(stream, other);
}
return stream << ')';
}
constexpr int mxn = 100'010;
constexpr int mxlog = 20;
int n, q, k;
int timer = 0;
vii adj[mxn];
int pre[mxn][mxlog];
int dep[mxn]{};
int tin[mxn];
int qry[mxn];
int freq[mxn]{};
vi res;
bool comp(const int &a, const int &b) {
return tin[a] < tin[b];
}
void dfs1(int cur, int prv) {
tin[cur] = timer++;
pre[cur][0] = prv;
for(int i = 1; i < mxlog; i++)
pre[cur][i] = pre[pre[cur][i - 1]][i - 1];
for(auto &[nxt, idx] : adj[cur]) {
if(nxt == prv)
continue;
dep[nxt] = 1 + dep[cur];
dfs1(nxt, cur);
}
}
void dfs2(int cur, int prv) {
for(auto &[nxt, idx] : adj[cur]) {
if(nxt == prv)
continue;
dfs2(nxt, cur);
if(freq[nxt] >= 2*k) {
res.pb(idx);
}
freq[cur] += freq[nxt];
}
assert(freq[cur] % 2 == 0);
}
int ances(int u, int d) {
for(int i = mxlog - 1; i >= 0; i--) {
if(d & (1 << i))
u = pre[u][i];
}
return u;
}
int LCA(int u, int v) {
if(dep[u] > dep[v])
swap(u, v);
v = ances(v, dep[v] - dep[u]);
if(u == v)
return u;
for(int i = mxlog - 1; i >= 0; i--) {
if(pre[u][i] != pre[v][i]) {
u = pre[u][i];
v = pre[v][i];
}
}
assert(pre[u][0] == pre[v][0]);
return pre[u][0];
}
void query() {
int m; cin >> m;
for(int i = 0; i < m; i++) {
cin >> qry[i], --qry[i];
}
sort(qry, qry + m, comp);
qry[m] = qry[0];
for(int i = 0; i < m; i++) {
int &u = qry[i];
int &v = qry[i + 1];
int mid = LCA(u, v);
++freq[u]; ++freq[v];
freq[mid] -= 2;
}
}
inline void solve() {
cin >> n >> q >> k;
for(int i = 1, u, v; i < n; i++) {
cin >> u >> v, --u, --v;
adj[u].pb(v, i);
adj[v].pb(u, i);
}
dfs1(0, 0);
while(q--)
query();
dfs2(0, 0);
cout << res.size() << '\n';
for(auto &e : res)
cout << e << ' ';
cout << '\n';
}
int main(int argc, char *argv[]) {
// #ifndef ONLINE_JUDGE
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
// #endif
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
solve();
return 0;
}
