#include<bits/stdc++.h>
#define ll long long
#define task ""
using namespace std;
const int maxn = 1e6 + 2, LG = 21, blocksize = 450, mod = 1e9 + 7;
int n, q, k, u, v, s, a, d[maxn], t = 0, tin[maxn], tout[maxn], st[LG][maxn], ps[maxn], res = 0;
vector<int> ok, L;
vector<pair<int, int>> adj[maxn];
void dfs (int u, int p)
{
tin[u] = ++t;
st[0][u] = p;
for (auto pp : adj[u])
{
int v = pp.first;
if (v == p) continue;
d[v] = d[u] + 1;
dfs(v, u);
}
tout[u] = t;
}
bool cmp (int x, int y)
{
return tin[x] < tin[y];
}
int lca (int u, int v)
{
if (d[u] < d[v]) swap(u, v);
int diff = d[u] - d[v];
for (int j = LG - 1; j >= 0; j--)
if (diff >= (1 << j))
{
diff -= (1 << j);
u = st[j][u];
}
if (u == v) return u;
for (int j = LG - 1; j >= 0; j--)
if (st[j][u] != st[j][v])
{
u = st[j][u];
v = st[j][v];
}
return st[0][u];
}
void dfs2 (int u, int p)
{
for (auto pp : adj[u])
{
int v = pp.first, i = pp.second;
if (v == p) continue;
dfs2(v, u);
if (ps[v] >= 2*k)
{
res++;
L.push_back(i);
}
ps[u] += ps[v];
}
}
int main ()
{
//freopen(task".INP", "r", stdin);
//freopen(task".OUT", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> q >> k;
for (int i = 1; i < n; i++)
{
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
}
dfs(1, 0);
for (int j = 1; j < LG; j++)
for (int i = 1; i <= n; i++)
st[j][i] = st[j - 1][st[j - 1][i]];
while (q--)
{
ok.clear();
cin >> s;
while (s--)
{
cin >> a;
ok.push_back(a);
}
sort(ok.begin(), ok.end(), cmp);
ok.resize(unique(ok.begin(), ok.end()) - ok.begin());
for (int i = 0; i < (int)ok.size(); i++)
{
int l = lca(ok[i], ok[(i + 1)%ok.size()]);
ps[ok[i]]++;
ps[l]--;
ps[ok[(i + 1)%ok.size()]]++;
ps[l]--;
}
}
dfs2(1, 0);
cout << res << '\n';
sort(L.begin(), L.end());
for (int i : L) cout << i << " ";
}
