#include <bits/stdc++.h>
using namespace std;
long long c,x,y,z,n,m,k;
int i,j;
long long h[1000001],up[100005][22],f[1000001],q[1000001];
typedef pair<int,int>i2;
vector<i2>a[1000001];
vector<int>pq,e[1000001];
set<int>s[1000001];
bool ok[1000001],ok1[1000001],d[1000001];
void dfs(int u)
{
for (int i=0;i<a[u].size();i++)
{
int v=a[u][i].second;
if (v==up[u][0]) continue;
h[v]=h[u]+1;
up[v][0]=u;
for (int j=1;j<=20;j++)
up[v][j]=up[up[v][j-1]][j-1];
dfs(v);
}
}
int lca(int u,int v)
{
if (h[u]!=h[v])
{
if (h[u]<h[v]) swap(u,v);
int k=(h[u]-h[v]);
for (int i=0;(1<<i)<=k;i++)
{
if (k>>i&1) u=up[u][i];
}
}
if (u==v) return u;
int k=__lg(h[u]);
for (int i=k;i>=0;i--)
{
if (up[u][i]!=up[v][i])
{
u=up[u][i]; v=up[v][i];
}
}
return up[u][0];
}
void dfs1(int u,int pre)
{
//cout<<u<<" "<<ok[u]<<"\n";
ok1[u]=ok[u];
//cout<<u<<" "<<a[u].size()<<"\n";
for (int i=0;i<a[u].size();i++)
{
int v=a[u][i].second;
//cout<<u<<" "<<v<<"\n";
if (v==pre) continue;
dfs1(v,u);
//cout<<v<<" "<<ok1[v]<<"\n";
if (ok1[v]==1)
{
d[a[u][i].first]=1;
//cout<<u<<" "<<v<<"\n";
}
ok1[u]=max(ok1[u],ok1[v]);
}
}
void dfs2(int u,int pre)
{
for (int i=0;i<a[u].size();i++)
{
int v=a[u][i].second;
if (v==pre) continue;
dfs2(v,u);
//if (u==4) cout<<u<<" "<<v<<"\n";
f[a[u][i].first]=s[v].size();
if (s[u].size()<s[v].size()) swap(s[u],s[v]);
for (auto i=s[v].begin();i!=s[v].end();i++)
{
s[u].insert(*i);
}
}
//if (u==4) cout<<s[u].size()<<"\n";
for (int i=0;i<e[u].size();i++)
{
auto id=s[u].find(e[u][i]);
s[u].erase(id);
}
// cout<<u<<"\n";
// for (auto i=s[u].begin();i!=s[u].end();i++)
// cout<<*i<<" ";
// cout<<"\n";
}
void sub1()
{
for (int i=1;i<=m;i++)
{
cin>>z;
for (int j=1;j<=z;j++)
{
cin>>q[j]; ok[q[j]]=1;
}
dfs1(q[1],0);
for (int j=1;j<=n;j++)
{
if (d[j]==1) f[j]++;
//cout<<i<<" "<<j<<" "<<d[j]<<" "<<ok[j]<<" "<<ok1[j]<<"\n";
ok[j]=0; ok1[j]=0; d[j]=0;
}
//cout<<"\n";
}
for (int i=1;i<=n;i++)
{
if (f[i]>=k)
{
pq.push_back(i);
}
}
cout<<pq.size()<<"\n";
for (int i=0;i<pq.size();i++)
{
cout<<pq[i]<<" ";
}
}
void sub2()
{
for (int i=1;i<=m;i++)
{
cin>>z; c=0;
for (int j=1;j<=z;j++)
{
cin>>q[j];
if (j==1) c=q[j]; else c=lca(c,q[j]);
s[q[j]].insert(i);
}
e[c].push_back(i);
}
dfs2(1,0);
for (int i=1;i<=n;i++)
{
if (f[i]>=k) pq.push_back(i);
}
cout<<pq.size()<<"\n";
for (int i=0;i<pq.size();i++)
cout<<pq[i]<<" ";
}
int main()
{
//freopen("suaduong.inp", "r" ,stdin);
//freopen("suaduong.out", "w" ,stdout);
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin>>n>>m>>k;
for (int i=1;i<n;i++)
{
cin>>x>>y;
a[x].push_back({i,y});
a[y].push_back({i,x});
}
dfs(1);
if (n<=5000) sub1(); else
sub2();
//cerr<<"time:"<<0.001*clock()<<"\n";
}
