#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl "\n"
#define pb push_back
#define ff first
#define ss second
#define ii pair<int, int>
#define vi vector<int>
#define vii vector<pair<int, int>>
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define mii map<int, int>
#define rep(i, a, b) for (int i = a; i <= b; i++)
#define all(a, len) (a) + 1, (a) + len + 1
#define vall(a) (a).begin(), a.end()
const int INF = 4e18;
const int MOD = 1e9 + 7;
int n, m, k; const int mx = 1e5 + 3, LG = 17;
vector<ii> adj[mx];
int st[mx], en[mx], cnt = 0;
struct LCA {
int par[mx], h[mx], id_par[mx];
int up[mx][LG];
void dfs(int u) {
st[u] = ++cnt;
for (auto [v, id]: adj[u]) {
if (v == par[u]) continue;
h[v] = h[u] + 1;
id_par[v] = id;
par[v] = u;
dfs(v);
}
en[u]= cnt;
};
void preprocess() {
dfs(1);
for (int u = 1; u <= n; u++) up[u][0] = par[u];
for (int j = 1; j < LG; j++) {
for (int u = 1; u <= n; u++) {
up[u][j] = up[up[u][j - 1]][j - 1];
}
}
};
int ancestor_k(int u, int k) {
for (int j = 0; (1 << j) <= k; j++) {
if ((k >> j & 1)) u = up[u][j];
}
return u;
};
int lca(int u, int v) {
if (h[u] != h[v]) {
if (h[u] < h[v]) swap(u, v);
int k = h[u] - h[v];
u = ancestor_k(u, k);
}
if (u == v) return u;
int k = __lg(h[u]);
for (int j = k; j >= 0; j--) {
if (up[u][j] != up[v][j]) {
u = up[u][j]; v = up[v][j];
}
}
return up[u][0];
};
} lca;
struct BIT {
int n;
int bit[mx];
BIT(int n_ = mx) {
n = n_;
};
void update(int u, int val) {
int idx = u;
while (idx <= this->n) {
bit[idx] += val;
idx += (idx&(-idx));
}
}
int get(int p) {
int idx = p, ans = 0;
while (idx > 0) {
ans += bit[idx];
idx -= (idx&(-idx));
}
return ans;
}
int get(int l, int r) {
return get(r) - get(l-1);
}
} bit;
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr); cout.tie(nullptr);
cin >> n >> m >> k;
rep(i, 1, n-1) {
int u, v; cin >> u >> v;
adj[u].pb({v, i}); adj[v].pb({u, i});
}
lca.preprocess();
while (m--) {
int s; cin >> s;
vi vec;
rep(i, 1, s) {
int u; cin >> u; vec.pb(u);
}
sort(vec.begin(), vec.end(), [](int x, int y) {
return st[x] < st[y];
});
vec.pb(vec[0]);
for (int i = 0; i < s; i++) {
bit.update(st[vec[i]], 1);
bit.update(st[vec[i+1]], 1);
bit.update(st[lca.lca(vec[i], vec[i+1])], -2);
}
}
vi res;
rep(i, 1, n) if (bit.get(st[i], en[i]) >= k*2) {
res.pb(lca.id_par[i]);
}
sort(vall(res));
cout << res.size() << endl;
for (int u: res) cout << u << ' ';
return 0;
}
