#include "bits/stdc++.h"
using namespace std;
#define rep(i,a,b) for(int i=(a); i<(b); ++i)
#define all(x) x.begin(),x.end()
#define sz(x) int(x.size())
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;
int main(){
cin.tie(NULL),cin.sync_with_stdio(false);
int n,m,k; cin >> n >> m >> k;
map<pair<int,int>,int> to_input;
vvi adj(n);
rep(i,0,n-1){
int u,v; cin >> u >> v;
u--,v--;
adj[u].push_back(v);
adj[v].push_back(u);
if (u>v) swap(u,v);
to_input[{u,v}] = i;
}
int cc = 0;
vi d(n), vis(n), dfsord(n);
vvi par(__lg(n)+1,vi(n));
auto dfs = [&](int at, int dep, auto&& self) -> void {
vis[at] = 1;
d[at] = dep;
for(auto to : adj[at]) if (!vis[to]){
par[0][to] = at;
self(to,dep+1,self);
}
dfsord[at] = cc++;
};
dfs(0,0,dfs);
rep(i,0,__lg(n)) rep(j,0,n) par[i+1][j] = par[i][par[i][j]];
auto jmp = [&](int at, int k) -> int {
for(int i = 0; k; i++,k/=2) if (k&1) at = par[i][at];
return at;
};
auto lca = [&](int u, int v) -> int {
if (d[u] < d[v]) swap(u,v);
u = jmp(u,d[u]-d[v]);
if (u==v) return u;
for(int i = __lg(n); i; --i)
if (par[i][u] != par[i][v])
u = par[i][u], v = par[i][v];
return par[0][u];
};
vi cnt(n);
auto addpath = [&](int at, int rt) -> void {
if (d[at] <= d[rt]) return;
cnt[at]++;
cnt[rt]--;
};
rep(i,0,m){
int t; cin >> t;
vi a(t);
rep(i,0,t) cin >> a[i], a[i]--;
if (t<2) continue;
sort(all(a),[&](int u, int v){
return dfsord[u] < dfsord[v];
});
int llca = lca(a[0],a[1]);
addpath(a[0],llca);
addpath(a[1],llca);
rep(i,2,t){
int p1 = a[i-1], p2 = a[i];
int curlca = lca(p1,p2);
int mlca = lca(curlca,llca);
addpath(p2,curlca);
if (mlca != llca){
addpath(llca,mlca);
llca = mlca;
}
}
}
fill(all(vis),0);
auto prop = [&](int at, auto&& self) -> void {
vis[at] = 1;
for(auto to : adj[at]) if (!vis[to]){
self(to,self);
cnt[at] += cnt[to];
}
};
prop(0, prop);
vi ans;
rep(i,0,n) if (cnt[i] >= k) ans.push_back(i);
cout << sz(ans) << '\n';
for(auto c : ans) {
int ot = par[0][c];
if (c > ot) swap(c,ot);
cout << to_input[{c,ot}]+1 << ' ';
}
cout << '\n';
}
