#include<bits/stdc++.h>
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T>
bool chmax(T &val, T nv) {
return val < nv ? (val = nv, true) : false;
}
template<class T>
bool chmin(T &val, T nv) {
return nv < val ? (val = nv, true) : false;
}
using namespace std;
using ll = long long;
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void debug(auto L, auto R) { while (L < R) cerr << *L << " \n"[L+1==R], ++L; }
void kout(){ cerr << endl; }
template<class T1, class ...T2> void kout(T1 a, T2 ...e) { cerr << a << ' ', kout(e...); }
#else
#define DE(...) 0
#define debug(...) 0
#endif
// What I should check
// 1. overflow
// 2. corner cases
// Enjoy the problem instead of hurrying to AC
// Good luck !
int32_t main() {
ios_base::sync_with_stdio(0), cin.tie(0);
int n, m, k;
cin >> n >> m >> k;
vector<vector<int>> edge(n+1), req(m);
vector<pair<int,int>> alle(n);
for (int a, b, i = 1;i < n;++i) {
cin >> a >> b;
alle[i] = {a, b};
edge[a].pb(b), edge[b].pb(a);
}
for (auto &vec : req) {
int len; cin >> len;
vec.resize(len);
for (int &u : vec) cin >> u;
}
const int mxlg = __lg(n);
vector<int> in(n+1), out(n+1), dfs_order;
vector<ll> pf(n+1);
vector<vector<int>> anc(mxlg + 1, vector<int>(n+1));
dfs_order.reserve(n);
function<void(int,int)> dfs = [&](int x, int lst) {
static int t;
in[x] = ++t;
anc[0][x] = lst;
for (int u : edge[x]) if (u != lst)
dfs(u, x);
out[x] = ++t;
dfs_order.pb(x);
};
dfs(1, 1);
for (int d = 1;d <= mxlg;++d)
for (int i = 1;i <= n;++i)
anc[d][i] = anc[d-1][ anc[d-1][i] ];
auto isanc = [&](int a, int b) { return in[a] <= in[b] && out[a] >= out[b]; };
auto getlca = [&](int a, int b) {
for (int d = mxlg;d >= 0;--d)
if (!isanc(anc[d][a], b))
a = anc[d][a];
return isanc(a, b) ? a : anc[0][a];
};
//for (int i = 1;i <= n;++i) DE(i, in[i], out[i]);
vector<ll> bitval(n*2+1);
vector<pair<int,ll>> allop;
auto add = [&](int i, ll v) {
allop.pb(i, v);
for (;i <= n*2;i += i&-i) bitval[i] += v;
};
auto reset = [&]() {
for (auto [i, v] : allop) add(i, -v);
allop.clear();
};
auto qry = [&](int i) {
ll res = 0;
for (;i;i ^= i&-i) res += bitval[i];
return res;
};
auto cmp1 = [&](int x, int y) {
return in[x] < in[y];
};
auto cmp2 = [&](int x, int y) {
return out[x] < out[y];
};
for (auto &vec : req) {
sort(AI(vec), cmp1);
for (int u : vec)
add(u, 1), ++pf[u];
vector<int> par;
for (int i = 0;i < vec.size();++i) for (int j = i+1;j < vec.size();++j)
par.pb(getlca(vec[i], vec[j]));
// for (int i = 1;i < vec.size();++i)
// par.pb(getlca(vec[i-1], vec[i]));
sort(AI(par), cmp2);
par.resize(unique(AI(par)) - begin(par));
debug(AI(par));
for (int u : par) {
int dn = qry(out[u]) - qry(in[u]-1), to_add = (u != par.back()) - dn;
DE(u, dn, to_add);
pf[u] += to_add;
add(u, to_add);
}
//for (int i = 1;i <= n;++i) DE(i, qry(out[i]) - qry(in[i]-1));
reset();
//break;
}
for (int u : dfs_order) if (u != 1) pf[ anc[0][u] ] += pf[u];
for (int i = 1;i <= n;++i) DE(i, pf[i]);
vector<int> res;
for (int i = 1;i < n;++i) {
auto &[a, b] = alle[i];
// I want a is up
if (in[a] > in[b]) swap(a, b);
if (pf[b] >= k) res.pb(i);
}
cout << res.size() << '\n';
for (int u : res) cout << u << " \n"[u == res.back()];
}
