#include <bits/stdc++.h>
#define fast ios::sync_with_stdio(0); cin.tie(NULL);cout.tie(NULL)
#define sz(x) (int)((x).size())
#define pb push_back
#define vi vector<int>
#define vb vector<bool>
#define vvb vector<vb>
#define pi pair<int,int>
#define vpi vector<pi>
#define vvi vector<vi>
#define vc vector<char>
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define pbb() pop_back()
#define f first
#define s second
#define ll long long
#define int long long
#define ull unsigned long long
#define line cout<<"_____________________________"<<endl;
#define forr(i, a, b) for(int i=a; i<b; i++)
const int N=1e5+1, mod=1e9+7, inf=1e18+1;
using namespace std;
vpi out[N];
int f[N]={0};
int n, m,k;
bool take[N];
vpi a;
void init()
{
forr(i, 0, N) take[i]=0;
}
void dfs(int u, int p)
{
if(take[u]) for(int i=sz(a)-1; i>=0 and a[i].s==0; i--)
{
f[a[i].first]++;
a[i].second=1;
}
for(pi v: out[u]) if(p!=v.f)
{
a.pb({v.s, 0});
dfs(v.f, u);
}
a.pbb();
}
void task()
{
cin>>n>>m>>k;
forr(i, 1, n)
{
int u, v;
cin>>u>>v;
out[u].pb({v,i});
out[v].pb({u,i});
}
while (m--)
{
int s;
cin>>s;
init();
int start=-1;
while(s--)
{
cin>>start;
take[start]=1;
}
dfs(start, 0);
a.clear();
}
vi b;
for(int i=1; i<n; i++) if(f[i]>=k) b.pb(i);
cout<<sz(b)<<endl;
for(int t: b) cout<<t<<' ';
cout<<endl;
}
signed main()
{
fast;
int t;
t=1;
//cin>>t;
while(t--)task();
}
