#include <bits/stdc++.h>
//#pragma GCC target("sse,sse2,avx2")
#pragma GCC optimize("unroll-loops,O3")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define all(x) (x).begin() , (x).end()
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pll;
constexpr int N = 1e5+20,mod = 1e9+7,inf = 1e9+10,sq = 500;
inline int mkay(int a,int b){
if (a+b >= mod) return a+b-mod;
if (a+b < 0) return a+b+mod;
return a+b;
}
inline int poww(int a,int k){
if (k < 0) return 0;
int z = 1;
while (k){
if (k&1) z = 1ll*z*a%mod;
a = 1ll*a*a%mod;
k >>= 1;
}
return z;
}
int tin[N],T,par[N][20],h[N],calc[N],k;
vector<pll> adj[N];
vector<int> ans;
inline int lca(int u,int v){
if (h[u] > h[v]) swap(u,v);
repr(i,19,0){
if (h[v]-h[u] >= (1 << i))
v = par[v][i];
}
if (u == v) return v;
repr(i,19,0){
if (par[v][i] != par[u][i]){
v = par[v][i];
u = par[u][i];
}
}
return par[v][0];
}
void dfs2(int v,int p){
for (pll u : adj[v]){
if (u.X != p){
dfs2(u.X,v);
if (calc[u.X]/2 >= k) ans.pb(u.Y);
calc[v] += calc[u.X];
}
}
}
void dfs(int v,int p){
par[v][0] = p;
tin[v] = T;
T++;
for (pll u : adj[v]){
if (u.X != p){
h[u.X] = h[v]+1;
dfs(u.X,v);
}
}
}
inline bool cmp(int i,int j){
return (tin[i] < tin[j]);
}
int main(){
ios :: sync_with_stdio(0); cin.tie(0);
int n,m;
cin >> n >> m >> k;
rep(i,1,n){
int u,v;
cin >> u >> v;
adj[u].pb({v,i});
adj[v].pb({u,i});
}
dfs(1,0);
rep(j,1,20){
rep(i,2,n+1)
par[i][j] = par[par[i][j-1]][j-1];
}
rep(x,0,m){
int s;
cin >> s;
vector<int> ve;
rep(j,0,s){
int v;
cin >> v;
ve.pb(v);
}
sort(all(ve),cmp);
rep(i,1,s){
int u = ve[i],v = ve[i-1],w = lca(u,v);
if (w == v){
calc[u]++;
calc[v]--;
continue;
}
calc[v]++;
calc[u]++;
calc[w] -= 2;
}
int u = ve[s-1],v = ve[0],w = lca(u,v);
if (v == w){
calc[u]++;
calc[v]--;
continue;
}
calc[u]++;
calc[v]++;
calc[w] -= 2;
}
dfs2(1,0);
sort(all(ans));
cout << ans.size() << endl;
for (int i : ans) cout << i << ' ';
}
