#include<bits/stdc++.h>
#define X first
#define Y second
#define all(x) begin(x), end(x)
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define FORD(i, b, a) for(int i = (b); i >= (a); i--)
#define REP(i, a, b) for (int i = (a); i < (b); i++)
#define mxx max_element
#define mnn min_element
#define SQR(x) (1LL * (x) * (x))
#define MASK(i) (1LL << (i))
#define Point Vector
#define left Left
#define right Right
#define div Div
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
typedef pair<db, db> pdb;
typedef pair<ld, ld> pld;
typedef pair<int, int> pii;
typedef pair<int, pii> piii;
typedef pair<ll, ll> pll;
typedef pair<ll, pll> plll;
typedef pair<ll, int> pli;
typedef pair<ll, pii> plii;
template<class A, class B>
bool maximize(A& x, B y) {
if (x < y) return x = y, true; else return false;
}
template<class A, class B>
bool minimize(A& x, B y) {
if (x > y) return x = y, true; else return false;
}
/* END OF TEMPLATE */
const int N = 1e5 + 7;
int P[N][20], high[N];
int n, m, k;
int last_edge[N];
vector<pii> v[N];
map<int, int> mp[N];
void dfs(int x, int par) {
P[x][0] = par;
for (int i = 1; i < 18; i++) P[x][i] = P[P[x][i - 1]][i - 1];
for (auto y : v[x])
if (y.X != par) {
high[y.X] = high[x] + 1;
last_edge[y.X] = y.Y;
dfs(y.X, x);
}
}
int LCA(int u, int v) {
if (high[u] > high[v]) swap(u, v);
int h = high[v] - high[u];
for (int i = 0; i < 18; i++)
if (h & MASK(i)) v = P[v][i];
if (u == v) return u;
for (int i = 17; i >= 0; i--)
if (P[u][i] != P[v][i]) u = P[u][i], v = P[v][i];
return P[u][0];
}
void update(int x, int y, int w) {
mp[x][w]++;
mp[y][w]++;
mp[LCA(x, y)][w]-=2;
}
vector<int> res;
void DFS(int x, int par) {
for (auto y : v[x])
if (y.X != par) {
DFS(y.X, x);
if ((int)mp[x].size() < (int)mp[y.X].size()) swap(mp[x], mp[y.X]);
for (auto tmp : mp[y.X]) {
mp[x][tmp.X]+=tmp.Y;
if (mp[x][tmp.X] == 0) mp[x].erase(mp[x].find(tmp.X));
}
}
if (mp[x].size() >= k) res.push_back(last_edge[x]);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin>>n>>m>>k;
for (int i = 1; i < n; i++) {
int x, y;
cin>>x>>y;
v[x].push_back({y, i});
v[y].push_back({x, i});
}
dfs(1, 1);
for (int t = 1; t <= m; t++) {
int s;
cin>>s;
set<int> tmp;
while (s--) {
int x;
cin>>x;
tmp.insert(x);
}
vector<int> a(tmp.begin(), tmp.end());
for (int i = 1; i < a.size(); i++) update(a[i - 1], a[i], t);
}
DFS(1, 1);
sort(all(res));
cout<<res.size()<<"\n";
for (auto x : res) cout<<x<<" ";
return 0;
}
