#include <bits/stdc++.h>
#define _FILE "TEMP"
#define ll long long
#define ii pair<int,int>
#define lii pair<ll,ll>
#define fi first
#define se second
#define MASK(i) (1ll << (i))
#define BIT(x, i) (((x) >> (i)) & 1)
using namespace std;
int n,m; ll k;
vector<ii> a[100007];
int cnt_id = 0;
int id[100007];
int rid[100007];
int par[100007];
int h[100007];
int head[100007];
int sz[100007];
int edge[100007];
int s;
int b[100007];
bool cmp(int a, int b) {
return id[a] < id[b];
}
void dfs(int i) {
sz[i] = 1;
for (ii &x : a[i]) {
int j = x.fi;
int e = x.se;
if (j == par[i]) continue;
par[j] = i;
h[j] = h[i] + 1;
edge[j] = e;
dfs(j);
sz[i] += sz[j];
if (sz[j] > sz[a[i][0].fi] || a[i][0].fi == par[i]) swap(x,a[i][0]);
}
}
void hld(int i) {
id[i] = ++cnt_id;
rid[cnt_id] = i;
for (ii x : a[i]) {
int j = x.fi;
if (j == par[i]) continue;
head[j] = (j == a[i][0].fi ? head[i] : j);
hld(j);
}
}
ll lazy[400007];
void push(int id) {
lazy[2*id] += lazy[id];
lazy[2*id+1] += lazy[id];
lazy[id] = 0;
}
void update(int id, int l, int r, int u, int v, ll val) {
if (l > v || u > r) return;
if (u <= l && r <= v) {
lazy[id] += val;
return;
}
int mid = (l + r) >> 1;
push(id);
update(2*id,l,mid,u,v,val);
update(2*id+1,mid+1,r,u,v,val);
}
vector<int> res;
void get(int id, int l, int r) {
if (l == r) {
int node = rid[l];
if (lazy[id] >= k) res.push_back(edge[node]);
return;
}
int mid = (l + r) >> 1;
push(id);
get(2*id,l,mid);
get(2*id+1,mid+1,r);
}
void up(int u, int v) {
while (head[u] != head[v]) {
if (h[head[u]] < h[head[v]]) swap(u,v);
update(1,1,n,id[head[u]],id[u],1);
u = par[head[u]];
}
if (h[u] < h[v]) swap(u,v);
update(1,1,n,id[v]+1,id[u],1);
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
#ifdef EMERGENCY_DEBUG
freopen(_FILE".inp","r",stdin);
freopen(_FILE".out","w",stdout);
#endif
cin >> n >> m >> k;
k *= 2;
for (int i=1; i<n; i++) {
int u,v;
cin >> u >> v;
a[u].push_back({v,i});
a[v].push_back({u,i});
}
dfs(1);
head[1] = 1;
hld(1);
while (m--) {
cin >> s;
for (int i=1; i<=s; i++) {
cin >> b[i];
}
sort(b+1,b+s+1,cmp);
for (int i=2; i<=s; i++) {
up(b[i-1],b[i]);
}
up(b[s],b[1]);
}
get(1,1,n);
cout << res.size() << '\n';
sort(res.begin(),res.end());
for (int i : res) cout << i << ' ';
return 0;
}
