#include<bits/stdc++.h>
using namespace std;
#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define ll long long
#define _ << " " <<
template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}
const int N=2e5+5;
const int LG=17;
int n,m,k;
int up[N][20],h[N],tin[N],tout[N],tim;
int st[N],top;
int val[N];
vector<ii> adj[N];
void dfs(int u, int p=0){
h[u]=h[p]+1;
up[u][0]=p;
foru(i,1,LG) up[u][i]=up[up[u][i-1]][i-1];
tin[u]=++tim;
for(auto [v,id]:adj[u])if(v!=p){
dfs(v,u);
}
tout[u]=tim;
}
int lca(int u, int v){
if(h[u]<h[v]) swap(u,v);
int d=h[u]-h[v];
foru(i,0,LG) if(bit(d,i)) u=up[u][i];
if(u==v)return u;
ford(i,LG,0) if(up[u][i]!=up[v][i])u=up[u][i],v=up[v][i];
return up[u][0];
}
vector<int> res;
void dfs2(int u, int p=0){
for(auto [v,id]:adj[u]) if(v!=p){
dfs2(v,u);
val[u]+=val[v];
if(val[v]>=k) res.eb(id);
}
}
void solve(){
cin>>n>>m>>k;
foru(i,1,n-1){
int u,v;cin>>u>>v;
adj[u].eb(v,i);
adj[v].eb(u,i);
}
dfs(1);
foru(i,1,m){
int s; cin>>s;
vector<int> lst;
foru(j,1,s){
int x; cin>>x;
lst.eb(x);
}
// continue;
sort(all(lst),[](int x, int y){return tin[x]<tin[y];});
foru(j,0,s-2){
lst.eb(lca(lst[j],lst[j+1]));
}
sort(all(lst),[](int x, int y){return tin[x]<tin[y];});
lst.erase(unique(all(lst)),lst.end());
// continue;
top=0;
for(int j:lst){
while(top && tout[st[top]]<tin[j])--top;
if(top) val[st[top]]--,val[j]++;
st[++top]=j;
}
}
dfs2(1);
cout<<sz(res)<<'\n';
sort(all(res));
for(int i:res)cout<<i<<" ";
cout<<'\n';
}
int32_t main(){
#define task "test"
if(fopen(task".inp","r")){
freopen(task".inp","r",stdin);
freopen(task".out","w",stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc=1; //cin>>tc;
rep(i,tc){
solve();
}
}
