#include <bits/stdc++.h>
// #pragma GCC optimize ("Ofast")
// #pragma GCC target ("avx,avx2")
using namespace std;
typedef long long ll;
typedef pair<int, int> pp;
#define rep(i,l,r) for(int i = (l); i < r; i++)
#define per(i,r,l) for(int i = (r); i >= l; i--)
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x).size()
#define pb push_back
#define ff first
#define ss second
const ll mod = 1e9 + 7, maxn = 2e5 + 2, lg = 20, inf = 1e9 + 5;
vector<pp> adj[maxn];
vector<int> ans;
int par[maxn][lg], st[maxn], t, h[maxn], val[maxn], k;
void dfs(int r, int p){
par[r][0] = p;
rep(i,1,lg) par[r][i] = par[par[r][i-1]][i-1];
st[r] = t++;
for(pp c: adj[r]) if(c.ff != p){
h[c.ff] = h[r] + 1;
dfs(c.ff, r);
}
}
int lca(int u, int v){
if(h[u] > h[v]) swap(u, v);
rep(i,0,lg) if((h[v] - h[u])>>i&1) v = par[v][i];
if(v == u) return u;
per(i,lg-1,0) if(par[u][i] != par[v][i]) u = par[u][i], v = par[v][i];
return par[u][0];
}
int dfs2(int r, int p){
int cr = 0;
for(pp c: adj[r]) if(c.ff != p){
int t = dfs2(c.ff, r);
if(t >= k << 1) ans.pb(c.ss);
cr += t;
}
cr += val[r];
return cr;
}
int main(){
cin.tie(0) -> sync_with_stdio(false);
int n, m; cin >> n >> m >> k;
rep(i,0,n-1){
int u, v; cin >> u >> v; u--, v--;
adj[u].pb({v, i});
adj[v].pb({u, i});
} dfs(0, 0);
rep(i,0,m){
int s; cin >> s;
vector<int> nd(s);
rep(i,0,s){
cin >> nd[i]; nd[i]--;
}
sort(all(nd), [&](int a, int b){
return st[a] < st[b];
});
rep(i,0,s){
int u = nd[i], v = nd[(i + 1)%s];
if(h[u] > h[v]) swap(u, v);
int l = lca(u, v);
if(l == u) val[l]--, val[v]++;
else val[l] -= 2, val[u]++, val[v]++;
}
} dfs2(0, 0);
sort(all(ans));
cout << sz(ans) << '\n';
for(int c: ans) cout << ++c << ' ';
return 0;
}
