#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vi> vii;
typedef pair<int,int> pi;
typedef vector<pi> pii;
typedef tuple<int,int,int> ti;
typedef vector<ll> li;
typedef vector<li> lii;
#define REP(i,a,b) for(int i=a;i<b;i++)
#define F first
#define S second
#define PB push_back
#define LSOne(s) ((s)&(-s))
ll INF=1000000000000000010;
int inf=1e9+10;
ll M=1e9+7;
int n,q,k,m;
vector<vector<pi>> a;
vector<pi> p;
vi num,cnt,low;
vii par;
int nm=0,lw=0;
void dfs(int x){
num[x]=nm++;
for(auto [u,v]:a[x])if(p[x].F!=u){
par[u][0]=x;
p[u]={x,v};
dfs(u);
}
low[x]=lw++;
}
void dfs2(int x){
for(auto [u,v]:a[x])if(p[x].F!=u){
dfs2(u);
cnt[x]+=cnt[u];
}
}
bool ances(int x,int y){
if(y==-1)return 1;
if(x==-1)return 0;
return (num[x]>=num[y]&&low[x]<=low[y]);
}
int LCA(int x,int y){
if(ances(x,y))return y;
if(ances(y,x))return x;
for(int i=m-1;i>=0;i--)if(!ances(x,par[y][i]))x=par[y][i];
return par[y][0];
}
int main() {
// ios::sync_with_stdio(0);
// cin.tie(0);
cin>>n>>q>>k;
m=log2(n)+1;
a.resize(n);p.resize(n,{-1,-1});num.resize(n);low.resize(n);
par.resize(n,vi(m,-1));
cnt.resize(n,0);
REP(i,0,n-1){
int x,y;cin>>x>>y;
x--;y--;
a[x].PB({y,i});
a[y].PB({x,i});
}
dfs(0);
REP(j,1,m)REP(i,0,n)if(par[i][j-1]!=-1)par[i][j]=par[par[i][j-1]][j-1];
while(q--){
int sz;cin>>sz;
vector<pi> arr;
REP(i,0,sz){
int y;cin>>y;
y--;
arr.PB({num[y],y});
}
sort(arr.begin(),arr.end());
arr.erase(unique(arr.begin(),arr.end()),arr.end());
reverse(arr.begin(),arr.end());
sz=arr.size();
REP(i,0,sz){
int x=arr[i].S,y=arr[(i+1)%sz].S;
int z=LCA(x,y);
cnt[x]++;
cnt[z]--;
}
}
dfs2(0);
vi ans;
REP(i,1,n)if(cnt[i]>=k)ans.PB(p[i].S);
sort(ans.begin(),ans.end());
cout<<ans.size()<<"\n";
for(auto u:ans)cout<<u+1<<" ";
}
