#include <bits/stdc++.h>
#define endl '\n'
#define fi first
#define se second
#define eb emplace_back
#define pb push_back
#define ALL(A) A.begin(), A.end()
#define FOR(i, l, r) for (int i = l; i <= r; i++)
#define FOR2(i, l, r) for (int i = l; i >= r; i--)
#define ce cout<<endl;
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
using pii = pair<int, int>;
using str = string;
using T = pair<ll,int>;
const ll INF = 1e18;
const int N = 1e5;
const int MAXM = 4200005;
const int LOG2 = 17;
const int inv = 1112;
const int MOD =998244353 ;
int dx[]= {0,0,-1,1};
int dy[] = {1 , - 1 , 0 , 0};
// Author : T_Danh - Tri An High School
ll mypow(ll a, ll b , ll mod ){
ll res = 1;
a %= mod;
while(b){
if(b & 1) res = res * a % mod;
a = a * a % mod;
b >>= 1;
}
return res;
}
int n ,m , k;
vector<pii> adj[N + 1];
int par[N + 1][LOG2 + 1];
int h[N + 1];
vector<int> sugg[N + 1];
int prefix[N + 1] , val[N + 1];
int ed[N + 1];
void dfs(int u , int p){
par[u][0] = p;
for(pii to :adj[u])if(to.fi != p){
h[to.fi] = h[u] + 1;
ed[to.fi] = to.se;
dfs(to.fi , u);
}
}
int LCA(int u , int v){
if(h[u] < h[v]) swap(u , v);
FOR2(i,LOG2 , 0){
if(h[u] - (1 << i) >= h[v]){
u = par[u][i];
}
}
if(u == v) return u;
FOR2(i,LOG2 , 0){
if(par[u][i] != par[v][i]){
u = par[u][i];
v = par[v][i];
}
}
return par[u][0];
}
set<int> cal(int u , int p){
set<int> cur;
for(int i : sugg[u]){
cur.insert(i);
}
for(pii to : adj[u]) if(to.fi != p){
set<int> tmp = cal(to.fi , u);
prefix[u] += prefix[to.fi];
if(tmp.size() > cur.size()) swap(cur , tmp);
for(int i : tmp) cur.insert(i);
}
val[u] = cur.size() + prefix[u];
return cur;
}
void solve() {
cin >> n >> m >> k;
FOR(i,1,n-1){
int u , v;
cin >> u >> v;
adj[u].eb(v , i);
adj[v].eb(u , i);
}
dfs(1,1);
FOR(j,1,LOG2){
FOR(i,1,n){
par[i][j] = par[par[i][j - 1]][j - 1];
}
}
FOR(i,1,m){
int s;
cin>>s;
int pre = -1;
FOR(j,1,s){
int x;
cin >> x;
if(pre == -1) pre = x;
else{
pre = LCA(pre , x);
}
sugg[x].eb(i);
}
prefix[pre] -= s;
}
cal(1,1);
vector<int> ans;
FOR(i,2,n){
if(val[i] >= k){
ans.eb(i);
}
}
cout << ans.size() <<endl;
for(int i : ans){
cout << ed[i] << " " ;
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define NAME "runaway"
if (fopen(NAME".in", "r"))
freopen(NAME".in", "r", stdin),
freopen(NAME".out", "w", stdout);
solve();
return 0;
}
