#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int,int>
#define pll pair<long long, long long>
#define fi first
#define se second
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define TASKNAME "NAME"
void init()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
///freopen(TASKNAME".INP","r",stdin); freopen(TASKNAME".OUT","w",stdout);
}
const int SZ = 1e5+5;
const ll INF = INT_MAX / 2, MOD = 1e9+7, INFLL = 2e18;
const double epsilon = 1e-3;
struct Edge
{
int v, id;
Edge(int _v = 0, int _id = 0) : v(_v), id(_id) {}
};
int n, m, k, num[SZ], s[SZ], up[SZ][18], h[SZ], timer = 0, c[SZ], b[SZ], sum[SZ];
vector<Edge> adj[SZ];
vector<int> a[SZ];
void dfs(int u, int prev)
{
num[u] = ++timer;
for(Edge e : adj[u])
{
int v = e.v, id = e.id;
if(v == prev) continue;
up[v][0] = u;
for(int i = 1; i < 18; i++)
{
up[v][i] = up[up[v][i-1]][i-1];
}
c[v] = id;
h[v] = h[u] + 1;
dfs(v, u);
}
}
int lca(int u, int v)
{
if(h[u] != h[v])
{
if(h[u] < h[v]) swap(u, v);
int diff = h[u] - h[v];
for(int i = 0; i < 18; i++)
{
if(diff >> i & 1) u = up[u][i];
}
}
if(u == v) return u;
for(int i = 17; i >= 0; i--)
{
if(up[u][i] != up[v][i])
{
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
void inc(int u, int v)
{
int p = lca(u, v);
b[u]++;
b[v]++;
b[p] -= 2;
}
bool cmp(int x, int y)
{
return num[x] < num[y];
}
void dfs2(int u, int prev)
{
sum[u] = b[u];
for(Edge e : adj[u])
{
int v = e.v;
if(v == prev) continue;
dfs2(v, u);
sum[u] += sum[v];
}
}
vector<int> res;
int main()
{
init();
cin >> n >> m >> k;
for(int i = 1; i < n; i++)
{
int u, v;
cin >> u >> v;
adj[u].pb({v, i});
adj[v].pb({u, i});
}
for(int i = 1; i <= m; i++)
{
cin >> s[i];
for(int j = 1; j <= s[i]; j++)
{
int x;
cin >> x;
a[i].pb(x);
}
}
dfs(1, 1);
for(int i = 1; i <= m; i++)
{
sort(all(a[i]), cmp);
a[i].pb(a[i][0]);
for(int j = 0; j < a[i].size() - 1; j++)
{
int u = a[i][j], v = a[i][j+1];
inc(u, v);
}
}
dfs2(1, 1);
for(int i = 2; i <= n; i++)
{
if(sum[i] >= k*2) res.pb(c[i]);
}
sort(all(res));
cout << res.size() << '\n';
for(int x : res) cout << x << " ";
}
