#include "bits/stdc++.h"
using namespace std;
#ifdef Nero
#include "Deb.h"
#else
#define deb(...)
#endif
template<typename T, class F = function<T(const T&, const T&)>>
struct SparseTable {
int n;
F func;
vector<vector<T>> mat;
SparseTable () {}
SparseTable (const vector<T>& a, F f) : func(f) {
n = (int) a.size();
int max_log = 32 - __builtin_clz(n);
mat.resize(max_log);
mat[0] = a;
for (int j = 1; j < max_log; ++j) {
mat[j].resize(n - (1 << j) + 1);
for (int i = 0; i <= n - (1 << j); ++i) {
mat[j][i] = func(mat[j - 1][i], mat[j - 1][i + (1 << (j - 1))]);
}
}
}
T get (int from, int to) {
assert(0 <= from && from <= to && to <= n - 1);
int lg = 31 - __builtin_clz(to - from + 1);
return func(mat[lg][from], mat[lg][to - (1 << lg) + 1]);
}
};
const int N = 100005;
vector<pair<int, int>> g[N];
signed main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
for(int i = 0; i < n - 1; ++i) {
int u, v;
cin >> u >> v;
g[u].emplace_back(v, i);
g[v].emplace_back(u, i);
}
int idd = 0;
vector<int> f(n + 1);
vector<int> dep(n + 1);
vector<int> o(2 * n - 1);
function<void(int, int)> Dfs = [&](int v, int p) {
f[v] = idd;
o[idd++] = v;
for (auto [u, i] : g[v]) {
if (u == p) {
continue;
}
dep[u] = dep[v] + 1;
Dfs(u, v);
o[idd++] = v;
}
};
Dfs(1, 1);
SparseTable<int> spa(o, [&](int x, int y) { return dep[x] < dep[y] ? x : y; });
auto Lca = [&](int u, int v) {
u = f[u], v = f[v];
if (u > v) swap(u, v);
return spa.get(u, v);
};
vector<int> dp(n + 1);
auto Add = [&](int u, int v) {
dp[u]++;
dp[v]++;
dp[Lca(u, v)] -= 2;
};
for (int i = 0; i < m; ++i) {
int s;
cin >> s;
vector<int> a(s);
for (int j = 0; j < s; ++j) {
cin >> a[j];
}
sort(a.begin(), a.end(), [&](int x, int y) { return f[x] < f[y]; });
for (int j = 1; j <= s; ++j) {
Add(a[j - 1], a[j % s]);
}
}
vector<int> ans;
function<int(int, int)> Dfs2 = [&](int v, int p) {
int ret = dp[v];
for (auto [u, i] : g[v]) {
if (u == p) {
continue;
}
int c = Dfs2(u, v);
ret += c;
if (c / 2 >= k) {
ans.push_back(i + 1);
}
}
return ret;
};
Dfs2(1, 1);
sort(ans.begin(), ans.end());
cout << ans.size() << '\n';
for (int i = 0; i < (int) ans.size(); ++i) {
cout << ans[i] << " \n"[i == (int) ans.size() - 1];
}
return 0;
}
