/* Author : Mychecksdead */
#include<bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef long double ld;
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define PI 3.1415926535
#define pb push_back
#define setp() cout << setprecision(15)
#define all(x) x.begin(), x.end()
#define oset tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define debug(x) cerr << #x << " is " << x << '\n';
const int N = 1e6+100, M = 1e5+10, F = 2147483646, K = 20;
int n, m, k, co[N], up[N][K], timer = 0, in[N], out[N];
vector<pair<int, int>> g[N];
vector<int> qq(N);
void pre(int v, int p){
in[v] = timer++;
up[v][0] = p;
for(auto u: g[v]){
if(u.first != p){
pre(u.first, v);
}
}
out[v] = timer++;
}
bool is_ancestor(int u, int v){
return in[u] <= in[v] && out[v] <= out[u];
}
int lca(int u, int v){
if(is_ancestor(u, v)) return u;
if(is_ancestor(v, u)) return v;
for(int j = K - 1; j >= 0; --j){
if(!is_ancestor(up[u][j], v)) u = up[u][j];
}
return up[u][0];
}
void dfs(int v, int p, int e){
for(auto u: g[v]){
if(u.first != p){
dfs(u.first, v, u.second);
qq[v] += qq[u.first];
}
}
co[e] = qq[v];
}
void solve(){
cin >> n >> m >> k;
for(int i = 0; i < n - 1; ++i){
int u, v; cin >> u >> v;
g[u].pb({v, i});
g[v].pb({u, i});
co[i] = 0;
}
pre(1, 1);
for(int j = 1; j < K; ++j){
for(int i = 1; i <= n; ++i) up[i][j] = up[up[i][j - 1]][j - 1];
}
for(int i = 0; i < m; ++i){
int c; cin >> c;
vector<int> v;
for(int j = 0; j < c; ++j){
int x; cin >> x; v.pb(x);
}
sort(all(v), [&](const int &a, const int &b){
return in[a] < in[b];
});
for(int j = 0; j < c; ++j){
int s = v[j], e = v[(j+1)%c];
int lc = lca(s, e);
qq[lc] -= 2;
qq[s]++, qq[e]++;
}
}
dfs(1, 1, n);
vector<int> ans;
for(int i = 0; i < n - 1; ++i) if(co[i] >= 2*k) ans.pb(i + 1);
cout << ans.size() << '\n';
for(int p: ans) cout << p << ' ';
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int T = 1, aa;
// cin >> T;aa=T;
while(T--){
// cout << "Case #" << aa-T << ": ";
solve();
cout << '\n';
}
return 0;
}
