#include <bits/stdc++.h>
#define ll long long
#define ii pair<ll,ll>
#define i3 pair<ii,ll>
#define fi first
#define se second
using namespace std;
int n,m,k;
vector<ii> a[100007];
int cnt, b[100007];
int id = 0;
int sta[100007], fin[100007];
int h[100007];
int par[100007][17];
ll pre[100007];
vector<int> res;
bool cmp(int a, int b) {
return sta[a] < sta[b];
}
int lca(int u, int v) {
if (h[u] < h[v]) swap(u,v);
int k = h[u] - h[v];
for (int i=0; (1<<i)<=k; i++) {
if ((k>>i)&1) u = par[u][i];
}
if (u == v) return u;
for (int i=__lg(h[u]); i>=0; i--) {
if (par[u][i] != par[v][i]) {
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
void dfs1(int i) {
sta[i] = ++id;
for (const ii &t : a[i]) {
int j = t.first;
if (j == par[i][0]) continue;
h[j] = h[i] + 1;
par[j][0] = i;
for (int k=1; k<=16; k++) {
par[j][k] = par[par[j][k-1]][k-1];
}
dfs1(j);
}
fin[i] = id;
}
void dfs2(int i) {
for (const ii &j : a[i]) {
if (j.fi == par[i][0]) continue;
dfs2(j.fi);
pre[i] += pre[j.fi];
if (pre[j.fi] >= k) res.push_back(j.se);
}
// cerr << i << ' ' << pre[i] << '\n';
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#ifdef EMERGENCY_DEBUG
freopen("TEMP.inp","r",stdin);
freopen("TEMP.out","w",stdout);
#endif
cin >> n >> m >> k;
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});
}
dfs1(1);
while (m--) {
cin >> cnt;
for (int i=1; i<=cnt; i++) {
cin >> b[i];
}
sort(b+1,b+cnt+1,cmp);
int u = lca(b[1],b[cnt]);
pre[b[1]]++;
pre[u]--;
for (int i=2; i<=cnt; i++) {
pre[b[i]]++;
pre[u]--;
int v = lca(b[i],b[i-1]);
pre[v]--;
pre[u]++;
}
}
dfs2(1);
cout << res.size() << '\n';
sort(res.begin(),res.end());
for (const int &i : res) cout << i << ' ';
return 0;
}
