#include <bits/stdc++.h>
using namespace std;
#define pii pair <int,int>
#define X first
#define Y second
const int N=1e5+5;
const int K=22;
int n,m,x,y,k,sz[N],h,H[N],p[N][K],t,c[N],e[N]; vector <int> g,w[N];; vector <pii> adj[N]; bool check[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;
e[v.X]=v.Y;
sz[u]+=sz[v.X];
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);
sz[u]+=sz[v.X];
if (sz[v.X]>=k) g.push_back(v.Y);
}
}
void lcb(int a)
{
while (!check[a])
{
check[a]=true;
g.push_back(e[a]);
a=p[a][0];
}
}
bool cmp(int x,int y)
{
return H[x]>H[y];
}
int main()
{
ios_base::sync_with_stdio(NULL);
cin.tie(NULL); cout.tie(NULL);
cin >> n >> m >> 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 j=1;j<=m;j++)
{
cin >> y;
for (int i=1;i<=y;i++)
{
cin >> x;
w[j].push_back(x);
}
t=max(t,y);
}
if (t==2)
{
for (int i=1;i<=m;i++)
if (w[i].size()==2)
{
sz[w[i][0]]++;
sz[w[i][1]]++;
sz[lca(w[i][1],w[i][0])]-=2;
}
}
else
{
t=0;
for (int i=1;i<=m;i++)
for (int j:w[i])
sz[j]++;
for (int i=1;i<=n;i++)
if (sz[i]>=k)
{
t++;
c[t]=i;
}
sort(c+1,c+t+1,cmp);
x=c[1];
for (int i=2;i<=t;i++)
x=lca(x,c[i]);
check[x]=true;
for (int i=1;i<=t;i++)
if (!check[c[i]]) lcb(c[i]);
}
sort(g.begin(),g.end());
cout << g.size() << "\n";
for (int i:g)
cout << i << ' ';
}
