#include <bits/stdc++.h>
using namespace std;
#define nl '\n'
template<class T> struct BIT {
vector<int> data; int N;
void init(int n) { N = n; data = vector<int>(N, 0); }
void add(int p, int x) { for(++p;p<=N;p+=p&-p) data[p-1] += x; }
int sum(int l, int r) { return sum(r+1) - sum(l); }
int sum(int r) { int s = 0; for(;r;r-=r&-r) s += data[r-1]; return s; }
};
int main() {
cin.tie(0)->sync_with_stdio(0);
int N, M, K; cin >> N >> M >> K;
vector<vector<int>> adj(N);
map<pair<int, int>, int> idx;
for(int i = 0; i < N-1; i++) {
int u, v; cin >> u >> v; --u, --v;
idx[{u, v}] = idx[{v, u}] = i;
adj[u].push_back(v);
adj[v].push_back(u);
}
const int LG = 20;
vector<vector<int>> up(N, vector<int>(LG));
vector<int> dep(N), st(N), en(N);
int t = 0;
function<void(int, int)> gen = [&](int u, int p) {
up[u][0] = (p == -1 ? u : p);
for(int i = 1; i < LG; i++) up[u][i] = up[up[u][i-1]][i-1];
dep[u] = (p == -1 ? 0 : dep[p]+1);
st[u] = t++;
for(auto v : adj[u]) if (v != p) gen(v, u);
en[u] = t-1;
};
gen(0, -1);
auto jmp = [&](int u, int d) {
for(int i = 0; i < LG; i++) if ((d >> i) & 1) u = up[u][i];
return u;
};
auto lca = [&](int u, int v) {
if (dep[u] < dep[v]) swap(u, v);
u = jmp(u, dep[u] - dep[v]);
if (u == v) return u;
for(int i = LG - 1; i >= 0; i--) {
int U = up[u][i], V = up[v][i];
if (U != V) u = U, v = V;
}
return up[u][0];
};
vector<int> C(N);
BIT<int> B; B.init(N);
for(int q = 0; q < M; q++) {
int k; cin >> k;
vector<int> A(k); for(auto &x : A) { cin >> x; --x; }
sort(begin(A), end(A), [&](int x, int y) {
if (en[x] == en[y]) return dep[x] > dep[y];
return en[x] < en[y];
});
int all = A[0];
// cout << q << " - " << k << nl;
for(auto x : A) {
all = lca(all, x);
B.add(st[x], 1);
C[x]++;
// cout << x << " ";
}
// cout << nl;
vector<int> L = A;
for(int i = 0; i < k-1; i++) {
L.push_back(lca(A[i], A[i+1]));
}
sort(begin(L), end(L));
L.erase(unique(begin(L), end(L)), end(L));
sort(begin(L), end(L), [&](int x, int y) {
if (en[x] == en[y]) return dep[x] > dep[y];
return en[x] < en[y];
});
// cout << "NODES: " << nl;
for(auto x : L) {
int amt = B.sum(st[x], en[x]) - 1;
// cout << x << " => " << amt << nl;
B.add(st[x], -amt);
C[x] -= amt;
}
// cout << nl;
C[all]--;
// cout << "LCA: " << all << nl;
for(auto x : L) B.add(st[x], -B.sum(st[x], st[x]));
}
vector<int> ans;
function<void(int, int)> dfs = [&](int u, int p) {
for(auto v : adj[u]) if (v != p) {
dfs(v, u);
C[u] += C[v];
}
// cout << u << " -> " << C[u] << nl;
if (p != -1 && C[u] >= K) ans.push_back(idx[{u, p}]);
};
dfs(0, -1);
sort(begin(ans), end(ans));
cout << size(ans) << nl;
for(auto x : ans) cout << x+1 << " ";
cout << nl;
return 0;
}
