#include <bits/stdc++.h>
using namespace std;
#define pii pair<int,int>
#define X first
#define Y second
const int N=1e5+5;
int n,q,k,x,y,p[N][22],m,t,H[N]; vector <pii> adj[N]; vector <int> del[N],ve; set <int> se[N];
void dfs(int u,int par)
{
for (pii v:adj[u])
if (v.X!=par)
{
H[v.X]=H[u]+1;
p[v.X][0]=u;
dfs(v.X,u);
}
}
int lca(int a,int b)
{
if (H[a]<H[b]) swap(a,b);
for (int j=20;j>=0;j--)
if (H[p[a][j]]>=H[b])
{
a=p[a][j];
}
if (a==b) return a;
for (int j=20;j>=0;j--)
if (p[a][j]!=p[b][j])
{
a=p[a][j];
b=p[b][j];
}
return p[a][0];
}
void calc(int u,int par)
{
for (pii v:adj[u])
if (v.X!=par)
{
calc(v.X,u);
if (se[v.X].size()>=k) ve.push_back(v.Y);
if (se[v.X].size()>se[u].size()) swap(se[v.X],se[u]);
for (int i:se[v.X])
se[u].insert(i);
}
for (int v:del[u])
se[u].erase(se[u].find(v));
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> q >> k;
for (int i=1;i<=n-1;i++)
{
cin >> x >> y;
adj[x].push_back(make_pair(y,i));
adj[y].push_back(make_pair(x,i));
}
H[1]=1;
dfs(1,-1);
for (int j=1;j<=20;j++)
for (int i=1;i<=n;i++)
p[i][j]=p[p[i][j-1]][j-1];
for (int i=1;i<=q;i++)
{
cin >> m;
t=n+1;
for (int j=1;j<=m;j++)
{
cin >> x;
se[x].insert(i);
if (t==n+1) t=x;
else t=lca(t,x);
}
del[t].push_back(i);
}
calc(1,-1);
sort(ve.begin(),ve.end());
cout << ve.size() << '\n';
for (int i=0;i<ve.size();i++)
cout << ve[i] << ' ';
}
