#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
int n,m,k,ord[100001],p[100001][18],cnt,sum[100001],level[100001];
vector<int> adj[100001],ans;
map<pii,int> mp;
void dfs(int x, int par) {
level[x]=level[par]+1;
p[x][0]=par;
for (int i=1; i<=17; ++i) p[x][i]=p[p[x][i-1]][i-1];
for (auto s : adj[x]) {
if (s==par) continue;
dfs(s,x);
}
ord[x]=++cnt;
}
int lca(int x, int y) {
if (level[x]<level[y]) swap(x,y);
int dif=level[x]-level[y];
for (int i=0; i<=17; ++i) {
if (dif&(1<<i)) x=p[x][i];
}
if (x==y) return x;
for (int i=17; i>=0; --i) {
if (p[x][i]!=p[y][i]) {
x=p[x][i];
y=p[y][i];
}
}
return p[x][0];
}
int dfs_ans(int x, int par) {
int cnt=sum[x];
for (auto s : adj[x]) {
if (s==par) continue;
cnt+=dfs_ans(s,x);
}
if (cnt>=k) ans.push_back(mp[pii(min(x,par),max(x,par))]);
return cnt;
}
void solve() {
vector<pii> v;
int s; cin>>s;
for (int i=1; i<=s; ++i) {
int x; cin>>x;
v.push_back(pii(ord[x],x));
}
sort(v.begin(),v.end());
int LCA=v[0].second;
for (int i=1; i<s; ++i) {
int llca=lca(v[i-1].second,v[i].second);
--sum[llca];
++sum[v[i].second];
if (level[llca]<level[LCA]) {
++sum[LCA];
--sum[llca];
LCA=llca;
}
}
}
int main() {
ios_base::sync_with_stdio(0);
cin>>n>>m>>k;
for (int i=1; i<=n-1; ++i) {
int a,b; cin>>a>>b;
adj[a].push_back(b);
adj[b].push_back(a);
if (a>b) swap(a,b);
mp[pii(a,b)]=i;
}
dfs(1,0);
while (m--) solve();
dfs_ans(1,0);
sort(ans.begin(),ans.end());
cout<<ans.size()<<"\n";
for (auto s : ans) cout<<s<<" ";
}
