#include <bits/stdc++.h>
#define FIXED_FLOAT(x) std::fixed <<std::setprecision(20) << (x)
#define all(v) (v).begin(), (v).end()
using namespace std;
#define forn(i,n) for (int i = 0; i < (n); ++i)
#define rforn(i, n) for(int i = (n) - 1;i >= 0;--i)
#define sz(x) (int)x.size()
using ll = long long;
int mod = (ll)1e9 + 7;
#define PI acos(-1)
typedef pair<int, int> pairs;
const int INF = 1e9 + 1;
const int N = 1e5 + 100;
const double eps = 1e-7;
template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;
template<class T, size_t SZ> using AR = array<T, SZ>;
template<class T> using PR = pair<T, T>;
template <typename XPAX>
bool ckma(XPAX &x, XPAX y) {
return (x < y ? x = y, 1 : 0);
}
template <typename XPAX>
bool ckmi(XPAX &x, XPAX y) {
return (x > y ? x = y, 1 : 0);
}
void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? "," : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#define debug(x...) cerr << "[" << #x << "] = ["; _print(x)
int n, l;
vector<vector<pairs>> g;
int timer;
vector<int> tin, tout;
vector<vector<int>> up;
vector<int> dep;
int name[N];
void dfs(int v, int p)
{
tin[v] = timer++;
dep[v] = (v == p ? 0 : dep[p] + 1);
up[v][0] = p;
for (int i = 1; i <= l; ++i)
up[v][i] = up[up[v][i-1]][i-1];
for (auto [u, id] : g[v]) {
if (u != p)
dfs(u, v), name[u] = id;
}
tout[v] = timer - 1;
}
bool is_ancestor(int u, int v)
{
return tin[u] <= tin[v] && tout[u] >= tout[v];
}
int lca(int u, int v)
{
if (is_ancestor(u, v))
return u;
if (is_ancestor(v, u))
return v;
for (int i = l; i >= 0; --i) {
if (!is_ancestor(up[u][i], v))
u = up[u][i];
}
return up[u][0];
}
void preprocess(int root) {
tin.clear();
tout.clear();
tin.resize(n);
tout.resize(n);
dep.clear();
dep.resize(n);
timer = 0;
l = ceil(log2(n));
up.assign(n, vector<int>(l + 1));
dfs(root, root);
}
struct FenwickTree {
vector<int> bit; // binary indexed tree
int n;
FenwickTree(int n) {
this->n = n;
bit.assign(n, 0);
}
FenwickTree(vector<int> a) : FenwickTree(a.size()) {
for (size_t i = 0; i < a.size(); i++)
add(i, a[i]);
}
int sum(int r) {
int ret = 0;
for (; r >= 0; r = (r & (r + 1)) - 1)
ret += bit[r];
return ret;
}
int sum(int l, int r) {
return sum(r) - sum(l - 1);
}
void add(int idx, int delta) {
for (; idx < n; idx = idx | (idx + 1))
bit[idx] += delta;
}
};
int ck[N];
void solve() {
int m, k;
cin >> n >> m >> k;
g.resize(n);
forn(i, n - 1) {
int a, b;
cin >> a >> b;
--a;--b;
g[a].push_back({b, i});
g[b].push_back({a, i});
}
preprocess(0);
FenwickTree F(n);
forn(pt, m) {
int s, ls;
cin >> s;
forn(i, s) cin >> ck[i], ck[i]--;
sort(ck, ck + s, [&](int a, int b) {return tin[a] < tin[b];});
ck[s] = ck[0];
forn(i, s) {
ls = lca(ck[i], ck[i + 1]);
F.add(tin[ck[i]], 1);
F.add(tin[ck[i + 1]], 1);
F.add(tin[ls], -2);
}
}
V<int> ans;
for(int i = 1;i < n;++i) if(F.sum(tin[i], tout[i]) >= 2 * k) ans.push_back(name[i]);
cout << sz(ans) << '\n';
for(auto c : ans) {
cout << c + 1 << ' ';
}
}
void test_case() {
int t;
cin >> t;
forn(p, t) {
//cout << "Case #" << p + 1 << ": ";
solve();
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
solve();
}
