#include<bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;
#define pb push_back
#define all(x) x.begin(), x.end()
const int MXN = 1e5+5;
const int LOG = 17;
int n, par[LOG][MXN], stt[MXN], fnt[MXN], timer;
vector<pii> g[MXN];
void dfs(int v) {
for(int i=1; i<LOG; i++)
par[i][v] = par[i-1][par[i-1][v]];
stt[v] = timer++;
for(auto [u, i] : g[v])
if(u!=par[0][v])
par[0][u]=v,
dfs(u);
fnt[v] = timer++;
}
bool is_anc(int u, int v) { return stt[u]<=stt[v] && fnt[v]<=fnt[u]; };
int LCA(int u, int v) {
if(is_anc(u, v)) return u;
for(int i=LOG-1; i>=0; i--)
if(par[i][u] && !is_anc(par[i][u], v))
u = par[i][u];
return par[0][u];
}
int k, ans[MXN];
void upd(int u, int v) {
ans[u]++;
ans[v]++;
ans[LCA(u,v)] -= 2;
}
vector<int> res;
void DFS(int v) {
for(auto [u, i] : g[v])
if(u!=par[0][v]) {
DFS(u);
if(ans[u]>=2*k) res.pb(i);
ans[v] += ans[u];
}
}
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
int m;
cin >> n >> m >> k;
for(int i=0, u,v; i<n-1; i++) {
cin >> u >> v;
g[u].pb(pii(v, i+1));
g[v].pb(pii(u, i+1));
}
dfs(1);
for(int t=0, s; t<m; t++) {
cin >> s;
vector<int> V(s);
for(int &v : V) cin >> v;
sort(all(V), [&](int u, int v) { return stt[u] < stt[v]; });
for(int i=0; i+1<s; i++)
upd(V[i], V[i+1]);
upd(V[0], V[s-1]);
}
DFS(1);
cout << res.size() << '\n';
for(int i : res) cout << i << ' ';
cout << '\n';
return 0;
}
