#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 n, m, k;
vector<pii> v[N];
namespace sub12 {
bitset<2007> bit[10007];
pii P[N];
void dfs(int x, int par) {
for (auto y : v[x])
if (y.X != par) {
P[y.X] = {x, y.Y};
dfs(y.X, x);
}
}
void update(int x, int y, int w) {
dfs(x, x);
while (y != x) {
bit[P[y].Y].set(w, 1);
y = P[y].X;
}
}
void Process() {
for (int t = 1; t <= m; t++) {
int s;
cin>>s;
vector<int> a(s, 0);
for (auto &x : a) cin>>x;
for (int i = 1; i < a.size(); i++) update(a[i - 1], a[i], t);
}
vector<int> res;
for (int i = 1; i < n - 1; i++)
if (bit[i].count() >= k) res.push_back(i);
cout<<res.size()<<"\n";
for (auto x : res) cout<<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});
}
if (n <= 10000) {
sub12::Process();
return 0;
}
return 0;
}
