#include "bits/stdc++.h"
using namespace std;
#define SZ(s) (int)s.size()
const int N = 1e5+5;
int n, m, k;
set <int> s[N];
vector <int> p, h, c;
vector <vector <int>> v, sp, v1;
map <pair<int,int>, int> mp;
void dfs(int x, int y = 0){
for(auto i : v[x]){
if(i == y) continue;
h[i] = h[x]+1;
p[i] = x;
dfs(i,x);
}
}
void df(int x, int y = 0){
for(auto i : v[x]){
if(i == y) continue;
df(i,x);
if(SZ(s[x]) < SZ(s[i])) swap(s[x], s[i]);
while(SZ(s[i]) > 0){
s[x].insert(*s[i].begin());
s[i].erase(s[i].begin());
}
}
while(SZ(v1[x]) > 0){
s[x].erase(s[x].find(v1[x].back()));
v1[x].pop_back();
}
if(SZ(s[x]) >= k) mp[{min(x,y), max(x,y)}] = 1;
return;
}
int lca(int x, int y){
if(h[x] < h[y]) swap(x,y);
for(int i = 20; i >= 0; i--){
if(h[sp[x][i]] >= h[y]) x = sp[x][i];
}
for(int i = 20; i >= 0; i--){
if(sp[x][i] != sp[y][i]) x = sp[x][i], y = sp[y][i];
}
if(x == y) return x;
return p[x];
}
int main(){
ios::sync_with_stdio(false); cin.tie(nullptr);
cin >> n >> m >> k;
v.resize(n+1), v1.resize(n+1);
sp.assign(n+1, vector <int> (25,0));
p.assign(n+1,0), h.assign(n+1,0), c.assign(n+1,0);
vector <int> u1(n+1), u2(n+1);
for(int i = 1; i < n; i++){
cin >> u1[i] >> u2[i];
v[u1[i]].push_back(u2[i]);
v[u2[i]].push_back(u1[i]);
}
h[1] = 1;
dfs(1);
for(int i = 1; i <= n; i++){
sp[i][0] = p[i];
}
for(int j = 1; j <= 20; j++){
for(int i = 1; i <= n; i++){
sp[i][j] = sp[sp[i][j-1]][j-1];
}
}
vector <int> a;
for(int i = 1; i <= m; i++){
int s1;
cin >> s1;
a.clear();
for(int j = 1; j <= s1; j++){
int x;
cin >> x;
a.push_back(x);
s[x].insert(i);
}
int lc = a[0];
for(int j = 1; j < s1; j++){
lc = lca(a[j], lc);
}
v1[lc].push_back(i);
}
df(1);
vector <int> v2;
for(int i = 1; i < n; i++){
if(mp[{min(u1[i], u2[i]), max(u1[i], u2[i])}] == true) v2.push_back(i);
}
cout << SZ(v2) << '\n';
for(auto i : v2){
cout << i << ' ';
}
return 0;
}
