#include <bits/stdc++.h>
#define F first
#define S second
#define pb push_back
#define ll long long
#define ii pair<int,int>
#define iii pair<int,pair<int,int>>
#define iil pair<ll,ll>
#define iiil pair<ll,pair<ll,ll>>
#define oo 1e18
#define check(n) (prime[n>>6]&(1<<((n&63)>>1)))
#define set(n) prime[n>>6]|=(1<<((n&63)>>1))
using namespace std;
const int N=2e5+5;
const ll Mod=1e9+7;
const ll MOD=13141702292180207;
const int dx[]={-1,0,0,1};
const int dy[]={0,-1,1,0};
int n,m,k,g[N],par[N][19],LOG=17, depth[N];
vector<ii> a[N];
set<int> d[N], dp[N];
vector<int> res;
void dfs(int u)
{
for (ii i: a[u])
{
int v=i.F;
if (v==par[u][0]) continue;
par[v][0]=u;
g[v]=i.S;
depth[v]=depth[u]+1;
dfs(v);
}
}
int lca(int u,int v)
{
if (depth[u]<depth[v]) swap(u,v);
for (int i=LOG;i>=0;i--)
if (depth[par[u][i]]>=depth[v]) u=par[u][i];
if (u==v) return v;
for (int i=LOG;i>=0;i--)
{
if (par[u][i]!=par[v][i])
{
u=par[u][i];
v=par[v][i];
}
}
return par[v][0];
}
void dfs2(int u)
{
for (ii i: a[u])
{
if (i.F==par[u][0]) continue;
dfs2(i.F);
for (int j: d[i.F]) d[u].insert(j);
}
for (int i: dp[u]) d[u].erase(i);
if (d[u].size()>=k) res.pb(g[u]);
// if (u==3)
// {
// cout << u << '\n';
// for (int i: d[u]) cout << i << ' ';
// }
// cout << '\n';
}
void slove()
{
cin >> n >> m >> k;
for (int i=1;i<n;i++)
{
int u,v;
cin >> u >> v;
a[u].pb(ii(v,i));
a[v].pb(ii(u,i));
}
g[1]=0; depth[1]=1;
par[1][0]=0;
dfs(1);
for (int j=1;j<=LOG;j++)
for (int i=1;i<=n;i++) par[i][j]=par[par[i][j-1]][j-1];
for (int j=1;j<=m;j++)
{
int x, u, v;
cin >> x;
for (int i=1;i<=x;i++)
{
cin >> u;
d[u].insert(j);
if (i==1) v=u;
else v=lca(v,u);
}
dp[v].insert(j);
}
dfs2(1);
cout << res.size() << '\n';
sort(res.begin(),res.end());
for (int i: res) cout << i << ' ';
}
int main()
{
//freopen("test.inp","r",stdin);
//freopen("test.out","w",stdout);
ios_base::sync_with_stdio(0);
cout.tie(0); cin.tie(0);
int T=1;
//cin >> T;
while(T--) slove();
}
