#include <bits/stdc++.h>
#define ll long long
#define s second
#define f first
#define pb push_back
#define pii pair <int,int>
#define int ll
using namespace std;
const int N = 1e5 + 5;
vector <int> v[N];
int timer,tin[N],tout[N],dep[N],d[25][N];
pii a[N];
int fen[N],p[N];
void dfs(int x,int par){
tin[x] = ++timer;
d[0][x] = par;
dep[x] = dep[par] + 1;
for (int to: v[x])
if (to != par) dfs(to,x);
tout[x] = timer;
}
void upd(int idx,int dl){
while (idx <= 100000){
fen[idx]+=dl;
idx+=(idx&(-idx));
}
}
int get(int idx){
int s = 0;
while (idx > 0){
s += fen[idx];
idx -= (idx & (-idx));
}
return s;
}
int lca(int x,int y){
if (dep[x] < dep[y]) swap(x,y);
for (int i = 18; i >= 0; i--)
if (dep[d[i][x]] >= dep[y]) x = d[i][x];
if (x == y) return x;
for (int i = 18; i >= 0; i--)
if (d[i][x] != d[i][y]) x = d[i][x],y = d[i][y];
return d[0][x];
}
void updatepath(int x,int y){
upd(tin[x],+1);
upd(tin[y],+1);
upd(tin[lca(x,y)],-2);
}
signed main(){
ios_base::sync_with_stdio(0),cin.tie(NULL),cout.tie(NULL);
int n,m,k;
cin>>n>>m>>k;
vector <pii> edges;
for (int i = 1; i < n; i++){
int a,b;
cin>>a>>b;
v[a].pb(b);
v[b].pb(a);
edges.pb({a,b});
}
dfs(1,1);
for (int j = 1; j <= 18; j++)
for (int i = 1; i <= n; i++)
d[j][i] = d[j - 1][d[j - 1][i]];
for (int i=0;i<edges.size();i++){
int x = edges[i].f,y = edges[i].s;
if (dep[x] < dep[y]) swap(x,y);
p[x] = i + 1;
}
for (int i = 1; i <= m; i++){
int t;
cin>>t;
for (int j = 1; j <= t; j++){
cin >> a[j].s;
a[j].f = tin[a[j].s];
}
sort(a+1,a+t+1);
for (int j = 2; j <= t; j++)
updatepath(a[j-1].s,a[j].s);
updatepath(a[t].s,a[1].s);
}
vector <int> ans;
for (int i = 2; i <= n; i++){
if (get(tout[i]) - get(tin[i] - 1) >= 2*k) ans.pb(p[i]);
}
cout<<ans.size()<<endl;
sort(ans.begin(),ans.end());
for (int x: ans)
cout<<x<<" ";
}
