#include<bits/stdc++.h>
using namespace std;
const int maxn=1e5+10;
map<pair<int,int>,int>imp;
set<pair<int,int>>s[maxn];
int minister[maxn], marc[maxn], tira[maxn], k;
vector<int>v[maxn], resp;
void merge(int pai, int filho){
int swp=0;
if(s[filho].size()>s[pai].size()){
swap(filho,pai);
swp++;
}
for(pair<int,int>p : s[filho]){
auto f=s[pai].lower_bound({p.first,0});
if(f==s[pai].end()||f->first!=p.first) s[pai].insert(p);
else{
if(f->second+p.second==minister[p.first]) tira[pai]++;
s[pai].insert({p.first,p.second+f->second});
s[pai].erase(f);
}
}
if(swp){
swap(s[pai],s[filho]);
swap(pai,filho);
}
s[filho].clear();
}
void dfs(int u, int pai){
marc[u]++;
for(int viz : v[u]){
if(viz==pai) continue;
dfs(viz,u);
merge(u,viz);
tira[u]+=tira[viz];
}
//cout << u << " " << s[u].size() << " " << tira[u] << endl;
if(s[u].size()-tira[u]>=k){
resp.push_back(imp[{u,pai}]);
}
}
int main(){
ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
int n, m; cin >> n >> m >> k;
for(int i=1;i<n;i++){
int a, b; cin >> a >> b;
v[a].push_back(b); v[b].push_back(a);
imp[{a,b}]=imp[{b,a}]=i;
}
for(int i=1;i<=m;i++){
int x; cin >> x;
for(int j=1;j<=x;j++){
int a; cin >> a;
s[a].insert({i,1});
}
minister[i]=x;
}
dfs(1,0);
sort(resp.begin(),resp.end());
cout << resp.size() << endl;
for(int a : resp) cout << a << " ";
cout << endl;
}
