#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef long long int ll;
typedef vector<ll> vi;
typedef vector<vector<ll>> vvi;
typedef pair<ll,ll> pi;
typedef map<ll,ll> mi;
typedef long double ld;
typedef vector<ld> vd;
typedef vector<vector<ld>> vvd;
typedef pair<ld,ld> pd;
#define ff first
#define ss second
#define srt(a) sort(a.begin(),a.end());
#define fip(k, n) for (ll i = k; i < n; i++)
#define fjp(k, n) for (ll j = k; j < n; j++)
#define fin(k, n) for (ll i = k; i >= n; i--)
#define fjn(k, n) for (ll j = k; j >= n; j--)
#define fp(k, n, m) for (ll k = n; k < m; k++)
#define fn(k, n, m) for (ll k = n; k >= m; k--)
#define ordered_set tree<pi, null_type,less< pi >, rb_tree_tag,tree_order_statistics_node_update>
#define totalOne(n) __builtin_popcount(n)
#define backZero(n) __builtin_ctzll(n)
#define frontZero(n) __builtin_clzll(n)
#define fx(k) for ( auto x : k )
#define test ll t;cin >> t;while (t--)
#define nli "\n"
// ==========================(debug)============================================================================================== //
#ifndef ONLINE_JUDGE
#define debug(x) cerr << #x <<" "; _printn(x); cerr << nli;
#else
#define debug(x)
#endif
void _printn(ll x){ cerr<<x<<" "; }
void _printn(int x){ cerr<<x<<" "; }
void _printn(ld x){ cerr<<x<<" "; }
void _printn(double x){ cerr<<x<<" "; }
void _printn(string x){ cerr<<x<<" "; }
void _printn(char x){ cerr<<x<<" "; }
void _printn(bool x){ cerr<<x<<" "; }
template<class T,class V>void _printn(pair<T,V> vv);
template<class T> void _printn(vector<T> vv);
template<class T> void _printn(set<T> vv);
template<class T,class V> void _printn(map<T,V> vv);
template<class T> void _printn(multiset<T> vv);
template<class T,class V>void _printn(pair<T,V> vv){ cerr<<"( ";_printn(vv.ff);cerr<<",";_printn(vv.ss);cerr<<")";}
template<class T> void _printn(vector<T> vv){ cerr<<"[ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"]"; };
template<class T> void _printn(set<T> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
template<class T> void _printn(multiset<T> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
template<class T,class V> void _printn(map<T,V> vv){ cerr<<"{ "; for(auto xx:vv){ _printn(xx);cerr<<" "; } cerr<<"}"; };
// ==========================(debug)============================================================================================== //
ll n,m,tp,tp2,res,cnt,sum,tptp,ans;
const ll mx = 5e5+5;
const ll mod = 1e9+7;
// ==========================(MOD)=============================================================================================== //
ll mod_add(ll aa,ll bb){ return ((aa%mod)+(bb%mod))%mod; }
ll mod_minus(ll aa,ll bb){ return (((aa%mod)-(bb%mod))+10*mod)%mod; }
ll mod_mul(ll aa,ll bb){ return ((aa%mod)*(bb%mod))%mod; }
ll mod_power(ll aa,ll bb){ aa%=mod; ll empowered = 1; bb%=mod-1; while(bb > 0){ if(bb & 1) empowered = mod_mul(empowered,aa); bb = bb >> 1; aa = mod_mul(aa,aa); } return empowered; }
ll mod_divi(ll aa,ll bb){ aa=mod_mul(aa,mod_power(bb,mod-2)); return aa; }
// ==========================(MOD)=============================================================================================== //
bool f = false;
ll k;
vi na;
vector<pi> adj[mx];
ll st[mx];
ll en[mx];
ll dep[mx];
ll up[mx][20];
int sr,de;
ll timer = 0;
ll val[mx];
ll dp[mx];
void dfs(ll u,ll par){
up[u][0] = par;
st[u] = timer;
timer++;
fjp(1,20)
up[u][j] = up[up[u][j-1]][j-1];
fx(adj[u])
if(x.ff!=par){
dep[x.ff] = dep[u] + 1;
dfs(x.ff,u);
}
en[u] = timer - 1;
return;
}
ll lca(ll aa,ll bb){
if(dep[aa] < dep[bb])
swap(aa,bb);
tptp = dep[aa] - dep[bb];
fjp(0,20)
if(tptp & (1<<j))
aa = up[aa][j];
if(aa==bb)
return aa;
fjn(19,0)
if(up[aa][j] != up[bb][j]){
aa = up[aa][j];
bb = up[bb][j];
}
return up[aa][0];
}
void dfs2(ll u,ll par){
fx(adj[u])
if(x.ff!=par){
dfs2(x.ff,u);
dp[u]+=dp[x.ff];
if(dp[x.ff]>=2*k)
na.push_back(x.ss);
}
return;
}
void upd(ll aa,ll bb){
res = lca(aa,bb);
dp[aa]++;
dp[bb]++;
dp[res]-=2;
return;
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
// #ifndef ONLINE_JUDGE
// freopen("input1.txt", "r", stdin);
// freopen("output1.txt", "w", stdout);
// freopen("error1.txt", "w", stderr);
// #endif // ONLINE_JUDGE
cin>>n>>m>>k;
fip(0,n-1){
cin>>sr>>de;
adj[sr].push_back({de,i});
adj[de].push_back({sr,i});
}
dep[1] = 0;
dfs(1,1);
vi a;
fip(0,m){
a.clear();
cin>>tp;
fjp(0,tp){
cin>>res;
a.push_back(res);
}
sort(a.begin(),a.end(),[](const ll &aa,const ll &bb){
return st[aa] < st[bb];
});
fip(0,tp)
upd(a[i],a[(i+1)%tp]);
}
dfs2(1,1);
srt(na);
cout<<(int)na.size()<<nli;
fx(na)
cout<<x+1<<" ";
// cerr << "Time elapsed: " << setprecision(6) << 1000.0 * clock() / CLOCKS_PER_SEC << "ms\n";
return 0;
}
