#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define ll long long
const ll sz=1e5+5;
ll p[sz], tt, pos[sz], in[sz], root;
vector<ll>g[sz], vec={0};
set<ll>s;
map<ll, ll>mp;
map<pair<ll, ll>, ll>m1;
/*
{} []
*/
void dfs(ll u, ll par)
{
vec.push_back(u);
pos[u]=++tt;
for(auto v:g[u]){
if(v!=par){
dfs(v, u);
}
}
}
int main()
{
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
ll n, m, k;
cin>>n>>m>>k;
for(int i=1; i<n; i++){
ll a, b;
cin>>a>>b;
g[a].push_back(b);
g[b].push_back(a);
m1[{a, b}]=i;
m1[{b, a}]=i;
in[a]++; in[b]++;
}
for(int i=1; i<=n; i++)
if(in[i]==1) root=i;
dfs(root, 0);
for(int i=1; i<=m; i++){
ll num;
cin>>num;
ll k[num+1];
for(int j=1; j<=num; j++){
cin>>k[j];
}
for(int j=2; j<=num; j++){
ll x=k[j-1], y=k[j];
ll a=pos[x], b=pos[y];
if(a>b) swap(a, b);
p[a]++; p[b]--;
}
}
for(int i=1; i<n; i++){
p[i]+=p[i-1];
mp[m1[{vec[i], vec[i+1]}]]+=p[i];
//cout<<p[i]<<' ';
}
for(auto i:mp){
if(i.second>=k){
s.insert(i.first);
}
}
cout<<s.size()<<endl;
for(auto i:s) cout<<i<<' ';
}
/*
{} []
4 3 3
2 1
1 4
4 3
3 1 2 3
2 1 4
2 2 3
*/
