#include <bits/stdc++.h>
#define pb push_back
using namespace std;
const int maxn = 1e5 + 1, maxLg = 20;
int n, q, k, timer, cnt[maxn], a[maxn], h[maxn], st[maxn], fn[maxn], par[maxn][maxLg];
vector <pair <int, int>> adj[maxn], check;
vector <int> res;
void dfs (int v, int p = 0){
st[v] = timer++;
par[v][0] = p;
for (int i = 1; i < maxLg; i++)
par[v][i] = par[par[v][i - 1]][i - 1];
for (auto [u, ind] : adj[v]){
if (u != p){
h[u] = h[v] + 1;
dfs(u, v);
}
}
fn[v] = timer++;
}
int lca (int x, int y){
if (h[x] < h[y])
swap(x, y);
if (st[x] <= st[y] && fn[x] >= fn[y])
return x;
for (int i = maxLg - 1; i >= 0; i--){
if (par[x][i] == 0)
continue;
int u = par[x][i];
if (!(st[u] <= st[y] && fn[u] >= fn[y]))
x = u;
}
return par[x][0];
}
void dfs2 (int v, int p = 0){
cnt[v] = a[v];
for (auto [u, ind] : adj[v]){
if (u == p)
continue;
dfs2(u, v);
if (a[u] >= 2 * k)
res.pb(ind);
a[v] += a[u];
}
// cnt[p] += cnt[v];
// if (cnt[v] >= 2 * k && ind > -1)
// res.pb(ind);
}
int main (){
ios_base::sync_with_stdio(0);
cin >> n >> q >> k;
for (int x, y, i = 0; i < n - 1; i++)
cin >> x >> y,
adj[x].pb({y, i}),
adj[y].pb({x, i});
dfs(1);
for (int s, i = 0; i < q; i++){
cin >> s;
for (int x, i = 0; i < s; i++)
cin >> x,
check.pb({st[x], x});
sort(check.begin(), check.end());
for (int i = 0; i < s; i++){
auto [v, u] = make_pair(check[i].second, check[(i + 1) % s].second);
a[v]++;
a[u]++;
a[lca(v, u)] -= 2;
}
check.clear();
}
dfs2(1);
cout << res.size() << '\n';
for (auto e : res)
cout << e + 1 << " ";
}
