#include <bits/stdc++.h>
using namespace std;
vector<long long> adj[200005];
long long visited, m=1, k=1, check[200005], tour[200005], nxt[200005], par[200005], sz[200005], pos[200005], chain[200005], head[200005], a[200005];
map<long long, long long> edge;
struct sortt
{
bool operator()(const long long &x, const long long &y) const
{
if (chain[x]==chain[y]) {return pos[x]>pos[y];}
else {return chain[x]>chain[y];};
};
};
multiset<long long, sortt> s;
vector<long long> ans;
void dfs(long long x, long long p)
{
par[x]=p;
sz[x]=1;
for (auto y: adj[x])
{
if (y!=p)
{
dfs(y, x);
sz[x]+=sz[y];
if (sz[y]>sz[nxt[x]]) {nxt[x]=y;};
};
};
}
void hld(long long x, long long p)
{
if (head[m]==0) {head[m]=x;};
chain[x]=m; tour[k]=edge[x*200000+p]; pos[x]=k; k++;
if (nxt[x]) {hld(nxt[x], x);};
for (auto y: adj[x])
{
if (y!=p && y!=nxt[x])
{
m++;
hld(y, x);
};
};
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
long long n, q, k, i, u, v;
cin >> n >> q >> k;
for (i=1; i<n; i++)
{
cin >> u >> v;
edge[u*200000+v]=edge[v*200000+u]=i;
adj[u].push_back(v);
adj[v].push_back(u);
};
dfs(1, 0);
hld(1, 0);
while (q--)
{
visited++;
cin >> u;
while (u--) {cin >> v; s.insert(v);};
while (chain[*s.begin()]!=chain[*prev(s.end())])
{
u=*s.begin();
if (check[chain[u]]!=visited) {a[pos[head[chain[u]]]]++; a[pos[u]+1]--; check[chain[u]]=visited;};
s.erase(*s.begin());
u=par[head[chain[u]]];
s.insert(u);
};
a[pos[*prev(s.end())]+1]++; a[pos[*s.begin()]+1]--;
s.clear();
};
for (i=1; i<=n; i++) {a[i]+=a[i-1]; if (a[i]>=k) {ans.push_back(tour[i]);};};
sort(ans.begin(), ans.end());
cout << ans.size() << "\n";
for (auto x: ans) {cout << x << " ";};
}
