#ifdef LOCAL
#include "local_header.h"
#include "debugger.h"
#else
#include <bits/stdc++.h>
#define debug(...)
#define DB(...)
#endif // LOCAL
using namespace std;
#define Task ""
struct __Init__ {
__Init__() {
cin.tie(nullptr)->sync_with_stdio(false);
if (fopen(Task".inp", "r")) {
freopen(Task".inp", "r", stdin);
freopen(Task".out", "w", stdout); }
}
} __init__;
using ll = long long;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define fi first
#define se second
#define For(i, l, r) for (int i = (l); i <= (r); ++i)
#define Ford(i, r, l) for (int i = (r); i >= (l); --i)
#define Rep(i, n) For (i, 0, (n) - 1)
#define Repd(i, n) Ford (i, (n) - 1, 0)
template<class C> int isz(const C& c) { return c.size(); }
template<class T> bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }
constexpr int eps = 1e-9;
constexpr int inf = 1e9;
constexpr ll linf = 1e18;
/// ============================================================================
constexpr int maxN = 1e5 + 5;
int n, m, k;
vector<pair<int, int>> g[maxN];
int s[maxN];
map<int, int> mp[maxN];
vector<int> ans;
void Dfs(int u, int p, int pid) {
for (const auto& e : g[u]) {
int v, id; tie(v, id) = e;
if (v == p) continue;
Dfs(v, u, id);
if (isz(mp[u]) < isz(mp[v])) {
mp[u].swap(mp[v]);
}
for (const auto& x : mp[v]) {
mp[u][x.fi] += x.se;
if (mp[u][x.fi] == s[x.fi]) mp[u].erase(x.fi);
}
}
if (isz(mp[u]) >= k) {
ans.push_back(pid);
}
}
signed main() {
cin >> n >> m >> k;
For (i, 1, n - 1) {
int u, v; cin >> u >> v;
g[u].emplace_back(v, i);
g[v].emplace_back(u, i);
}
For (i, 1, m) {
cin >> s[i];
Rep (_, s[i]) {
int u; cin >> u;
++mp[u][i];
}
}
ans.reserve(n);
Dfs(1, -1, -1);
cout << isz(ans) << '\n';
sort(all(ans));
for (int x : ans) cout << x << ' ';
}
/**
**/
