#include <bits/stdc++.h>
using namespace std;
vector<vector<int>> adj;
vector<vector<pair<int,int>>> spt;
vector<int> par,hvy,fst,grp,pew;
vector<pair<int,int>> et;
int hld(int c, int d) {
int s = 1, m = 0;
fst[c] = et.size();
et.push_back({d,c});
for (auto i : adj[c]) {
if (i==par[c]) continue;
par[i]=c;
int cs = hld(i,d+1);
et.push_back({d,c});
s+=cs;
if (cs>m) {
m=cs;
hvy[c]=i;
}
}
return s;
}
void sptb(int n) {
int mp = 1, mpi = 0;
while (mp<=(n<<1)-2) {
mp<<=1;
mpi++;
}
spt.resize(mpi);
for (int i = 0; i < (n<<1) - 1; i++) spt[0].push_back(et[i]);
for (int i = 1; i < mpi; i++) for (int j = 0; j <= (n<<1) - 1 - (1<<i); j++) spt[i].push_back(min(spt[i-1][j],spt[i-1][j+(1<<(i-1))]));
}
int lca(int a, int b) {
a = fst[a];
b = fst[b];
if (a>b) swap(a,b);
int s = 31-__builtin_clz(b-a+1);
return min(spt[s][a],spt[s][b+1-(1<<s)]).second;
}
void pa(int d, int a) {
while (et[fst[d]].first>et[fst[a]].first) {
if (d==grp[d]) {
pew[d]++;
d = par[d];
}
else {
int n = max(et[fst[grp[d]]],et[fst[a]]).second;
pew[hvy[n]]++;
if (hvy[d]>0) pew[hvy[d]]--;
d = n;
}
}
}
void decomp(int c, int g) {
grp[c] = g;
for (auto i : adj[c]) {
if (i==par[c]) continue;
if (i==hvy[c]) decomp(i,g);
else decomp(i,i);
}
}
int main() {
int n,m,k,i,e1,e2;
cin >> n >> m >> k;
adj.resize(n);
par.resize(n);
hvy.resize(n);
fst.resize(n);
grp.resize(n);
pew.resize(n);
int el[n-1][2];
for (i = 0; i < n-1; i++) {
cin >> e1 >> e2;
adj[--e1].push_back(--e2);
adj[e2].push_back(e1);
el[i][0] = e1;
el[i][1] = e2;
}
hld(0,0);
decomp(0,0);
sptb(n);
int pei[n];
for (i = 0; i < n-1; i++) pei[max(et[fst[el[i][0]]],et[fst[el[i][1]]]).second] = i+1;
for (int j = 0; j < m; j++) {
cin >> e1;
vector<pair<int,int>> qs(e1);
for (i = 0; i < e1; i++) {
cin >> e2;
qs[i] = et[fst[e2-1]];
}
sort(qs.begin(), qs.end());
int prev = qs[0].second, oca = prev, og = prev;
for (i = 1; i < e1; i++) {
oca = lca(oca,qs[i].second);
pa(qs[i].second,lca(qs[i].second,prev));
prev = qs[i].second;
}
pa(og,oca);
}
vector<int> id;
for (i = 1; i < n; i++) {
if (fst[i]==-1) continue;
else if (i==hvy[par[i]]) {
int c = grp[i], s = 0;
while (hvy[c]>0) {
c = hvy[c];
s += pew[c];
if (s>=k) id.push_back(pei[c]);
fst[c] = -1;
}
}
else if (pew[i]>=k) id.push_back(pei[i]);
}
cout << id.size() << endl;
sort(id.begin(), id.end());
for (auto i : id) cout << i << " ";
}
