#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ii pair<int,int>
#define fi first
#define se second
int d[100005], cnt[100005], mark[100005], msk, par[100005], a[100005];
vector <int> g[100005];
ii eg[100005];
void dfs(int u, int p = 0)
{
for (int id : g[u])
{
int v = eg[id].fi + eg[id].se - u;
if (v == p) continue;
d[v] = d[u] + 1;
par[v] = id;
dfs(v, u);
}
}
void proc(int u, int v)
{
while (u != v)
{
if (d[u] != d[v])
{
if (d[u] > d[v])
{
if (mark[par[u]] != msk)
{
cnt[par[u]]++;
mark[par[u]] = msk;
}
u = eg[par[u]].fi + eg[par[u]].se - u;
}
else
{
if (mark[par[v]] != msk)
{
cnt[par[v]]++;
mark[par[v]] = msk;
}
v = eg[par[v]].fi + eg[par[v]].se - v;
}
} else
{
if (mark[par[u]] != msk)
{
cnt[par[u]]++;
mark[par[u]] = msk;
}
u = eg[par[u]].fi + eg[par[u]].se - u;
if (mark[par[v]] != msk)
{
cnt[par[v]]++;
mark[par[v]] = msk;
}
v = eg[par[v]].fi + eg[par[v]].se - v;
}
}
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
int n, m, k; cin >> n >> m >> k;
for (int i = 1; i < n; i++)
{
int u, v; cin >> u >> v;
eg[i] = {u, v};
g[u].push_back(i);
g[v].push_back(i);
}
dfs(1);
for (int l = 1; l <= m; l++)
{
msk = l;
int x; cin >> x;
for (int i = 1; i <= x; i++) cin >> a[i];
for (int i = 2; i <= x; i++) proc(a[1], a[i]);
}
vector <int> vec;
for (int i = 1; i < n; i++) if (cnt[i] >= k) vec.push_back(i);
cout << vec.size() << '\n';
for (int x : vec) cout << x << ' ';
}
