#include<bits/stdc++.h>
#define pb push_back
#define x first
#define y second
using namespace std;
const int N = 100005, LG = 17;
int n, q, k, ts, A[N], st[N], en[N], H[N], P[N][LG], R[N];
vector < pair < int , int > > Adj[N];
void DFS(int v, int p)
{
st[v] = ts ++;
P[v][0] = p;
for (int i = 1; i < LG; i++)
P[v][i] = P[P[v][i - 1]][i - 1];
for (auto &u : Adj[v])
if (u.x != p)
H[u.x] = H[v] + 1, DFS(u.x, v);
en[v] = ts;
}
inline int LCA(int v, int u)
{
if (H[v] < H[u])
return (LCA(u, v));
for (int i = 0; i < LG; i++)
if ((H[v] - H[u]) & (1 << i))
v = P[v][i];
if (v == u)
return (v);
for (int i = LG - 1; ~ i; i --)
if (P[v][i] != P[u][i])
v = P[v][i], u = P[u][i];
return (P[v][0]);
}
inline bool CMP(int i, int j)
{
return (st[i] < st[j]);
}
void FNL(int v, int id)
{
for (auto &u : Adj[v])
if (u.y != id)
{
FNL(u.x, u.y);
A[v] += A[u.x];
}
R[id] = A[v];
}
int main()
{
scanf("%d%d%d", &n, &q, &k);
for (int i = 1; i < n; i++)
{
int a, b;
scanf("%d%d", &a, &b);
Adj[a].pb({b, i});
Adj[b].pb({a, i});
}
DFS(1, 0);
for (int i = 1; i <= q; i++)
{
int m;
scanf("%d", &m);
vector < int > vec(m);
for (int j = 1; j <= m; j++)
scanf("%d", &vec[j - 1]);
sort(vec.begin(), vec.end(), CMP);
for (int j = 0; j < m; j++)
vec.pb(LCA(vec[j], vec[(j + 1) % m]));
sort(vec.begin(), vec.end(), CMP);
vec.resize(unique(vec.begin(), vec.end()) - vec.begin());
if ((int)vec.size() <= 1)
continue;
vector < int > stk; stk.pb(vec[0]);
for (int j = 1; j < (int)vec.size(); j++)
{
while (stk.size() && en[stk.back()] < en[vec[j]])
stk.pop_back();
A[vec[j]] ++;
A[stk.back()] --;
stk.pb(vec[j]);
}
}
FNL(1, 0);
vector < int > vec;
for (int i = 1; i < n; i++)
if (R[i] >= k)
vec.pb(i);
printf("%d\n", (int)vec.size());
for (int id : vec)
printf("%d ", id);
return 0;
}
