#include<iostream>
#include<vector>
#include<cstdio>
#include<algorithm>
using namespace std;
int n, m, k, myClock;
//indexed by n
vector<vector<int> > T, ID, ministersInCity; // ,ministersForWhichThisCityIsImportant;
vector<bool> onDFSStack;
vector<int> pre, post, val;
vector<vector<pair<int, int> > > importantCityList;
//indexed by m
vector<vector<int> > importantCitiesOfMinister;
vector<int> possibleRootOfMinister;
//general
vector<int> importantTracks, DFSStack;
// DEBUGGING
void printvec(string s, vector<int> v) {
cout << s;
for(int i = 0; i < v.size(); ++i) cout << " " << v[i];
cout << endl;
}
void printvecvec(string s, vector<vector<int> > v) {
cout << s << endl;
for(int i = 0; i < v.size(); ++i) {
cout << i;
printvec(":", v[i]);
}
}
void initialize() {
scanf("%d%d%d", &n, &m, &k);
onDFSStack = vector<bool> (n, false);
pre = vector<int> (n, 0);
post = vector<int> (n, 0);
val = vector<int> (n, 0);
T = vector<vector<int> > (n, vector<int>());
ID = vector<vector<int> > (n, vector<int>());
ministersInCity = vector<vector<int> > (n, vector<int>());
// for each city, a list of pairs (minister for which this city is important, ID of this city in that ministers important city list)
importantCityList = vector<vector<pair<int, int> > > (n, vector<pair<int, int> > ());
for(int i = 1; i <= n-1; ++i) {
int u, v;
scanf("%d%d", &u, &v);
T[--u].push_back(--v);
T[v].push_back(u);
ID[u].push_back(i);
ID[v].push_back(i);
}
possibleRootOfMinister = vector<int> (m, -1);
importantCitiesOfMinister = vector<vector<int> > (m, vector<int>());
for(int i = 0; i < m; ++i) {
int si;
scanf("%d", &si);
for(int j = 0; j < si; ++j) {
int city;
scanf("%d", &city);
ministersInCity[--city].push_back(i);
}
}
}
// prePostDFS
void prePostDFS(int pos) {
pre[pos] = ++myClock;
onDFSStack[pos] = true;
for(int i = 0; i < T[pos].size(); ++i) {
int ch = T[pos][i];
if(onDFSStack[ch]) continue;
prePostDFS(ch);
}
onDFSStack[pos] = false;
post[pos] = ++myClock;
}
void importantCityDFS(int pos) {
onDFSStack[pos] = true;
for(int i = 0; i < ministersInCity[pos].size(); ++i) {
int minister = ministersInCity[pos][i];
while(!importantCitiesOfMinister[minister].empty() && post[importantCitiesOfMinister[minister].back()] > pre[pos]) {
importantCitiesOfMinister[minister].pop_back(); }
importantCitiesOfMinister[minister].push_back(pos);
}
for(int i = 0; i < T[pos].size(); ++i) {
int ch = T[pos][i];
if(onDFSStack[ch]) continue;
importantCityDFS(ch);
}
for(int i = 0; i < ministersInCity[pos].size(); ++i) {
int minister = ministersInCity[pos][i];
possibleRootOfMinister[minister] = pos;
}
onDFSStack[pos] = false;
}
void setPositiveValues() {
for(int i = 0; i < m; ++i) {
for(int j = 0; j < importantCitiesOfMinister[i].size(); ++j) {
val[importantCitiesOfMinister[i][j]]++;
}}
}
void setImportantCityList() {
for(int i = 0; i < m; ++i) {
for(int j = 0; j < importantCitiesOfMinister[i].size(); ++j) {
int thisCity = importantCitiesOfMinister[i][j];
importantCityList[thisCity].push_back(pair<int, int> (i, j));
}}
}
bool isAncestorOf(int possibleParent, int possibleChild) {return post[possibleParent] > post[possibleChild];}
// computes the LCA of DFSStack[pos] and targetCity, assuming the LCA is abovr or equal to pos on the DFSStack,
// and below (bigger than) or including lb.
int LCA(int pos, int lb, int targetCity) {
int city = DFSStack[pos];
//cout << "LCA(" << pos << " " << lb << " " << targetCity << ")" << endl;
if(lb + 1 >= pos) {
if(isAncestorOf(city, targetCity)) return city;
return DFSStack[lb];
}
int test = (pos + lb) / 2;
int testCity = DFSStack[test];
if(isAncestorOf(testCity, targetCity)) {return LCA(pos, test, targetCity);}
return LCA(test, lb, targetCity);
}
void setNegativeValueDFS(int pos) {
DFSStack.push_back(pos);
onDFSStack[pos] = true;
for(int i = 0; i < importantCityList[pos].size(); ++i) {
int minister = importantCityList[pos][i].first;
int j = importantCityList[pos][i].second;
if(j + 1 == importantCitiesOfMinister[minister].size()) continue;
int nextCity = importantCitiesOfMinister[minister][j+1];
// LCA of pos and nextCity:
int stackSize = DFSStack.size();
//cout << "computing LCA of " << pos << " " << " and " << nextCity << endl;
int minusPos = LCA(stackSize - 1, 0, nextCity);
// update possible root of minister
if(post[minusPos] > post[possibleRootOfMinister[minister]]) possibleRootOfMinister[minister] = minusPos;
// decrease value!
//cout << "decreasing city # " << minusPos << " for minister " << minister << endl;
val[minusPos]--;
}
for(int i = 0; i < T[pos].size(); ++i) {
int ch = T[pos][i];
if(onDFSStack[ch]) continue;
setNegativeValueDFS(ch);
}
onDFSStack[pos] = false;
DFSStack.pop_back();
}
void setNegativeRootValues() {
for(int i = 0; i < m; ++i) {val[possibleRootOfMinister[i]]--;}
}
int findTargetEdgeDFS(int pos, int edgeID) {
onDFSStack[pos] = true;
int myVal = val[pos];
for(int i = 0; i < T[pos].size(); ++i) {
int ch = T[pos][i];
int chID = ID[pos][i];
if(onDFSStack[ch]) continue;
myVal += findTargetEdgeDFS(ch, chID);
}
//cout << "pos " << pos << " myVal " << myVal << endl;
if(myVal >= k) importantTracks.push_back(edgeID);
onDFSStack[pos] = false;
return myVal;
}
int main() {
initialize();
//printvecvec("T:", T);
//printvecvec("Ministers In City:", ministersInCity);
prePostDFS(0);
importantCityDFS(0);
//printvecvec("Important Cities", importantCitiesOfMinister);
setPositiveValues();
//printvec("Only positive values: ", val);
setImportantCityList();
setNegativeValueDFS(0);
//printvec("Values after removing LCA's: ", val);
//printvec("Roots", possibleRootOfMinister);
setNegativeRootValues();
//printvec("Values: ", val);
int dummy = findTargetEdgeDFS(0, -1);
sort(importantTracks.begin(), importantTracks.end());
printf("%d\n", importantTracks.size());
for(int i = 0; i + 1 < importantTracks.size(); ++i) {printf("%d ", importantTracks[i]);}
if(importantTracks.size() != 0) {
printf("%d\n", importantTracks[importantTracks.size() - 1]);
}
}
