#include <bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
using namespace std;
#define int long long
#define pb push_back
#define nl '\n'
#define fore(i, y) for(int i = 0; i < y; i++)
#define forr(i, x, y) for(int i = x;i<=y;i++)
#define forn(i, y, x) for(int i = y; i >= x; i--)
const int N = 1e5 + 10;
const int LOG = 19;
vector<int> adj[N];
int par[LOG][N];
int pref[N];
int tin[N];
int dep[N];
int Time = -1;
bool cmp(const int &a , const int &b)
{
return tin[a] < tin[b];
}
void dfs(int x , int p)
{
Time++;
tin[x] = Time;
for(auto u : adj[x])
{
if(u == p)
continue;
par[0][u] = x;
forr(j , 1 ,LOG - 1)
{
par[j][u] = par[j - 1][par[j - 1][u]];
}
dep[u] = dep[x] + 1;
dfs(u , x);
}
}
int lift(int x , int k)
{
fore(i , LOG)
{
if((1<<i) & k)
x = par[i][x];
}
return x;
}
int lca(int a , int b)
{
if(dep[a] < dep[b])
swap(a , b);
int x = dep[a] - dep[b];
a = lift(a , x);
if(a == b)
return a;
forn(i , LOG -1 , 0)
{
int na = par[i][a] , nb = par[i][b];
if(na == nb)
continue;
a = na , b = nb;
}
return par[0][a];
}
int re_dfs(int x , int p)
{
for(auto u : adj[x])
{
if(u == p)
continue;
re_dfs(u , x);
pref[x]+=pref[u];
}
}
map<pair<int ,int> , int> edges;
signed main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n , m , k;
cin>>n>>m>>k;
fore(i , n - 1)
{
int u , v;
cin>>u>>v;
u-- , v--;
edges[{u , v}] = edges[{v , u}] = i;
adj[u].pb(v);
adj[v].pb(u);
}
dfs(0 , -1);
fore(i , m)
{
int s;
cin>>s;
vector<int> nodes(s);
for(auto &x : nodes)
{
cin>>x;
x--;
}
sort(nodes.begin() , nodes.end() , cmp);
nodes.pb(nodes[0]);
fore(j ,s)
{
int a = nodes[j] , b = nodes[j + 1];
int mid = lca(a , b);
pref[mid]-=2;
pref[a]++;
pref[b]++;
}
}
re_dfs(0, -1);
vector<int> ans;
forr(i ,1, n - 1)
{
if(pref[i] >= 2 * k)
{
ans.pb(edges[{i , par[0][i]}] + 1);
}
}
sort(ans.begin() , ans.end());
cout<<(int)ans.size()<<nl;
for(auto x : ans)
cout<<x<<" ";
}
