#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> ii;
typedef pair<ll, ii> iii;
#define pb push_back
#define fi first
#define se second
#define endl '\n'
#define MOD 1000000000
#define MASK(i) (1ll << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
ll n,m,k;
ll cnt;
ll c[100005];
ll h[100005];
ll f[100005];
ll tin[100005];
ll par[100005][20];
vector <ll> a[100005];
vector <ll> res;
map <ii,ll> mp;
void dfs(ll x,ll p){
tin[x] = ++cnt;
for (ll i : a[x]){
if (i == p) continue;
h[i] = h[x] + 1;
par[i][0] = x;
dfs(i,x);
}
}
void setup(){
for (long j=1; j<=18; j++){
for (long i=1; i<=n; i++){
par[i][j] = par[par[i][j-1]][j-1];
}
}
}
ll lca(ll u,ll v){
if (h[u] < h[v]) swap(u,v);
for (long i=18; i>=0; i--){
if (h[par[u][i]] >= h[v]) u = par[u][i];
}
if (u == v) return u;
for (long i=18; i>=0; i--){
if (par[u][i] != par[v][i]){
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
void dfs2(ll x,ll p){
for (ll i : a[x]){
if (i == p) continue;
dfs2(i,x);
f[x] += f[i];
} if (f[x] >= 2*k) res.pb(mp[{x,par[x][0]}]);
}
bool cmp(ll a,ll b){
return tin[a] < tin[b];
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (long i=1; i<n; i++){
ll u,v; cin >> u >> v;
a[u].pb(v);
a[v].pb(u);
mp[{u,v}] = mp[{v,u}] = i;
}
h[1] = 1;
dfs(1,0);
setup();
while (m--){
ll t; cin >> t;
for (long i=1; i<=t; i++) cin >> c[i];
sort(c+1,c+t+1,cmp);
c[t+1] = c[1];
for (long i=2; i<=t+1; i++){
f[c[i-1]]++;
f[c[i]]++;
f[lca(c[i-1],c[i])] -= 2;
}
}
dfs2(1,1);
cout << res.size() << endl;
sort(res.begin(),res.end());
for (ll it : res) cout << it << ' ';
}
