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