#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
int X = 18;
struct node{
vector<pii> to;
vector<int> father = *new vector<int>(X);
int with = -1, cnt = 0, d = -1, out = 0;
bool was = false;
};
vector<node> graph;
bool sortFunc(int a, int b){
return graph[a].out < graph[b].out;
}
int in = 0;
void DFS(int curr, int father){
graph[curr].was = true;
graph[curr].father[0] = father;
graph[curr].d = graph[father].d + 1;
for(int i = 1; i < X; i++)
graph[curr].father[i] = graph[graph[curr].father[i-1]].father[i-1];
for(pii& to : graph[curr].to)
if(!graph[to.first].was)
DFS(to.first, curr), graph[to.first].with = to.second;
graph[curr].out = in++;
graph[curr].was = false;
}
int lca(int a, int b){
if(graph[a].d < graph[b].d) swap(a,b);
for(int i = X-1; i >= 0; i--)
if(graph[graph[a].father[i]].d >= graph[b].d)
a = graph[a].father[i];
if(a == b) return a;
for(int i = X-1; i>= 0; i--)
if(graph[a].father[i] != graph[b].father[i])
a = graph[a].father[i], b = graph[b].father[i];
return graph[a].father[0];
}
int n,m,k;
vector<int> sol;
int count(int curr){
graph[curr].was = true;
for(pii& to : graph[curr].to)
if(!graph[to.first].was) graph[curr].cnt += count(to.first);
if(graph[curr].cnt >= k)
sol.push_back(graph[curr].with);
return graph[curr].cnt;
}
int main(){
cin>>n>>m>>k;
graph.resize(n+1);
for(int i = 1; i < n; i++){
int a,b;
cin>>a>>b;
graph[a].to.push_back({b,i});
graph[b].to.push_back({a,i});
}
DFS(1, 0);
while(m--){
int x;
cin>>x;
vector<int> here(x);
for(int& a : here) cin>>a, graph[a].cnt++;
sort(here.begin(), here.end(), sortFunc);
int l = here[0];
for(int i = 0; i < x-1; i++)
graph[lca(here[i], here[i+1])].cnt--, l = lca(l, here[i+1]);
graph[l].cnt--;
}
count(1);
cout<<sol.size()<<"\n";
for(int& a : sol) cout<<a<<" ";
cout<<"\n";
}
