#include <bits/stdc++.h>
#define NMAX 100000
#define LOG 10
#define ll long long int
#define BASE 32
#define MOD 1000000007
using namespace std;
ifstream fin("cod.in");
ofstream fout("cod.out");
vector<pair<int,int>> adj[NMAX+1];
int timer=0,euler[NMAX+1];
vector<int> In[NMAX+1],Out[NMAX+1];
int n,m,k;
int d[NMAX+1],parent[NMAX+1][LOG+1];
int Lca(int x,int y)
{
if(d[x] < d[y])
{
swap(x,y);
}
for(int i=LOG;i>=0;i--)
{
if(d[x]-(1<<i)>=d[y])
{
x = parent[x][i];
}
}
for(int i=LOG;i>=0;i--)
{
if(parent[x][i]!=parent[y][i])
{
x = parent[x][i];
y = parent[y][i];
}
}
if(x!=y)
{
x = parent[x][0];
}
return x;
}
void dfs1(int x,int p)
{
euler[x] = ++timer;
parent[x][0] = p;
d[x] = d[p] + 1;
for(auto e : adj[x])
{
if(e.first!=p)
{
dfs1(e.first,x);
}
}
}
vector<int> res;
map<int,int> mp[NMAX+1];
int cnt[NMAX+1];
void dfs(int x,int p)
{
for(auto [y,id] : adj[x])
{
if(y!=p)
{
dfs(y,x);
if(cnt[y]>=k)
{
res.push_back(id);
}
if(mp[y].size() > mp[x].size())
{
mp[x].swap(mp[y]);
cnt[x] = cnt[y];
}
for(auto j : mp[y])
{
int t = mp[x][j.first];
if(!t && j.second)
{
cnt[x]++;
}
mp[x][j.first] += j.second;
}
}
}
for(int j : In[x])
{
if(mp[x][j]==0)
{
cnt[x]++;
}
mp[x][j]++;
}
for(int j : Out[x])
{
if(mp[x][j]==1)
{
cnt[x]--;
}
mp[x][j]--;
}
}
int main()
{
cin >> n >> m >> k;
for(int i=1;i<n;i++)
{
int x,y;
cin >> x >> y;
adj[x].push_back({y,i});
adj[y].push_back({x,i});
}
dfs1(1,0);
for(int j=1;j<=LOG;j++)
{
for(int i=1;i<=n;i++)
{
parent[i][j] = parent[parent[i][j-1]][j-1];
}
}
for(int i=1;i<=m;i++)
{
vector<int> v;
int s;
cin >> s;
for(int j=1;j<=s;j++)
{
int x;
cin >> x;
v.push_back(x);
}
sort(v.begin(),v.end(),[](int a,int b){return euler[a] < euler[b];});
for(int j=1;j<v.size();j++)
{
int lca = Lca(v[j],v[j-1]);
Out[lca].push_back(i);
Out[lca].push_back(i);
In[v[j]].push_back(i);
In[v[j-1]].push_back(i);
}
}
dfs(1,0);
cout << res.size() << '\n';
sort(res.begin(),res.end());
for(int j : res)
{
cout << j << " ";
}
}
