#include <bits/stdc++.h>
using namespace std;
const int N=1e5+5;
typedef pair<int,int>i2;
long long c,d,x,y,z,n,q,m;
int i,j,k;
vector<i2>a[N];
vector<int>g[N],kq;
int up[N][22],h[N],b[N],canh[N];
set<int>st[N];
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;
canh[v]=a[u][i].first;
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)
{
for (int i=0;i<a[u].size();i++)
{
int v=a[u][i].second;
if (v==pre) continue;
dfs1(v,u);
if (st[u].size()<st[v].size()) swap(st[u],st[v]);
for (auto id:st[v])
st[u].insert(id);
}
for (int i=0;i<g[u].size();i++)
{
int x=g[u][i];
st[u].erase(st[u].find(x));
}
if (st[u].size()>=k) kq.push_back(canh[u]);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin>>n>>q>>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);
for (int rep=1;rep<=q;rep++)
{
cin>>m;
for (int i=1;i<=m;i++)
{
cin>>b[i];
if (i==1) c=b[i]; else c=lca(c,b[i]);
}
for (int i=1;i<=m;i++)
{
st[b[i]].insert(rep);
}
g[c].push_back(rep);
}
dfs1(1,0);
sort(kq.begin(),kq.end());
cout<<kq.size()<<"\n";
for (int i=0;i<kq.size();i++)
cout<<kq[i]<<" ";
}
