/*
ID: USACO_template
LANG: C++
PROG: USACO
*/
#include <iostream> //cin , cout
#include <fstream> //fin, fout
#include <stdio.h> // scanf , pringf
#include <cstdio>
#include <algorithm> // sort , stuff
#include <stack> // stacks
#include <queue> // queues
#include <map>
#include <string>
using namespace std;
typedef pair<int, int> pii;
typedef vector<int> vi; /// adjlist without weight
typedef vector<pii> vii; /// adjlist with weight
typedef vector<pair<int,pii>> vpip; /// edge with weight
typedef long long ll;
#define mp make_pair
#define fst first
#define snd second
#define pb push_back
#define sz(x) (int)(x).size()
#define trav(u, adj_v) for (auto& u: adj_v)
const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5; //
const ll INF = 1e18; //
#define MAXV 100007
#define MAXE 100007
const int xdir[4] = {1,0,-1,0}, ydir[4] = {0,1,0,-1}; /// 4 directions
struct NODE {
int x, y;
int val;
int visited;
bool operator< (NODE b) const { return (x == b.x) ? (y < b.y) : (x < b.x); }
};
struct EDGE {
int from, to;
ll weight;
bool operator<(EDGE other) const { return weight < other.weight; }
};
/// code from USACO examples
void setIO(string name) {
ios_base::sync_with_stdio(0); cin.tie(0);
freopen((name+".in").c_str(),"r",stdin);
freopen((name+".out").c_str(),"w",stdout);
}
bool debug = false, submit = true;
int N, M, K;
vi adjlist[MAXV];
map<int, int> pathmap[MAXV];
int dp[MAXV];
/// Euler ID for the tree
int p[MAXV], level[MAXV];
pii eulerRange[MAXV];
int eulerID = 0;
void buildEulerTree(int u, int lv) {
eulerID++;
eulerRange[u].first = eulerID;
for(int i=0; i<adjlist[u].size(); i++) {
int v = adjlist[u][i];
if(v != p[u]) {
p[v] = u;
level[v] = lv + 1;
buildEulerTree(v, lv+1);
}
}
eulerRange[u].second = eulerID;
}
void initEuler() {
/// root = 1
adjlist[1].push_back(0);
p[1] = 0; level[1] = 1; //p[0] = 0; level[0] = 0;
eulerID = 0;
buildEulerTree(1, 1);
}
bool cmdFunc(const int& v1, const int& v2) {
return eulerRange[v1].fst < eulerRange[v2].first;
}
/// tree info for calculate LCA
#define MAXLCALOG 20
int depth[MAXV], anc[MAXV][MAXLCALOG];
void prepLCA() {
for(int i = 1; i <= N; i++) { anc[i][0] = p[i]; depth[i] = level[i] - 1;}
for(int j = 1; j < MAXLCALOG; j++)
for(int i = 1; i <= N; i++)
anc[i][j] = anc[anc[i][j-1]][j-1];
}
int upD(int curr, int dist) { /// go up by dist
if(dist == 0) return curr;
for(int k = MAXLCALOG - 1; k>=0; k--) {
while(dist >= (1<<k) ) {
curr = anc[curr][k];
dist -= (1<<k);
}
if(dist == 0) return curr;
}
return curr;
}
int getP(int curr, int wantedDepth) { /// reach wanted depth
for(int k = MAXLCALOG - 1; depth[curr] != wantedDepth; k--) {
while(depth[curr] - (1<<k) >= wantedDepth) {
curr = anc[curr][k];
}
}
return curr;
}
int getLCA(int a, int b) {
if(depth[a] > depth[b]) {
return getLCA(b, a);
}
if(depth[a] < depth[b]) {
b = getP(b, depth[a]);
}
for(int k = MAXLCALOG - 1; k > 0; k--) {
while(anc[a][k] != anc[b][k]) {
a = anc[a][k];
b = anc[b][k];
}
}
while(a != b) {
a = p[a];
b = p[b];
}
return a;
}
vi ans;
int dfsDP(int v, int pv) {
if(sz(adjlist[v])==1 && v != 1) { // leaf
if(dp[v] >= 2*K) ans.pb(pathmap[v][pv]);
return dp[v];
}
for(int x : adjlist[v]) {
if(x == pv) continue;
dp[v] += dfsDP(x, v);
}
if(dp[v] >= 2*K && v != 1) ans.pb(pathmap[v][pv]);
return dp[v];
}
int main() {
debug = true; submit = false;
if(submit) setIO("testName");
int i, j, k;
cin >> N >> M >> K;
for(i=1; i<=N-1; i++) {
int a, b; cin >> a >> b;
adjlist[a].pb(b); adjlist[b].pb(a);
pathmap[a][b] = i; pathmap[b][a] = i;
}
initEuler();
prepLCA();
vi cmd;
for(i=1; i<=M; i++) {
cmd.clear();
int a; cin >> a;
for(j=0; j<a; j++) { int b; cin >> b; cmd.pb(b); }
sort(cmd.begin(), cmd.end(), cmdFunc);
int b = cmd[0]; cmd.pb(b);
for(j=0; j < sz(cmd) - 1; j++) {
a = cmd[j]; b = cmd[j+1];
int c = getLCA(a, b);
dp[a]++; dp[c]--;
dp[b]++; dp[c]--;
}
}
dfsDP(1, 0);
sort(ans.begin(), ans.end());
cout << sz(ans) << endl;
for(int x : ans) cout << x << " ";
cout << endl;
}
