#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int LG = 17;
int n, m, k, a[N], h[N], par[N][LG], st[N], ft[N], tme;
vector<int> g[N];
void dfs(int v, int p = -1){
st[v] = tme;
tme++;
for (int u : g[v]){
if (u == p) continue;
h[u] = h[v] + 1;
par[u][0] = v;
for (int i = 1; i < LG; i ++)
if (par[u][i - 1] != -1)
par[u][i] = par[par[u][i - 1]][i - 1];
dfs(u, v);
}
ft[v] = tme;
}
int get_anc(int v, int d){
for (int i = 0; i < LG; i ++)
if ((1 << i) & d)
v = par[v][i];
return v;
}
int lca(int u, int v){
if (h[u] > h[v])
swap(u, v);
v = get_anc(v, h[v] - h[u]);
for (int i = LG - 1; i >= 0; i --)
if (par[v][i] != par[u][i])
v = par[v][i], u = par[u][i];
return (u == v) ? v : par[v][0];
}
map<pair<int, int>, int> ind;
set<int> S[N], inside[N], ans;
void dfs_ans(int v, int p = -1){
for (int u : g[v]){
if (u == p) continue;
dfs_ans(u, v);
a[v] += a[u];
if (S[v].size() < S[u].size())
swap(S[u], S[v]);
for (int x : S[u])
S[v].insert(x);
S[u].clear();
}
for (int x : inside[v])
S[v].erase(x);
if (S[v].size() >= k and ~p)
ans.insert(ind[{p, v}]);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for (int i = 1; i < n; i ++){
int u, v;
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
ind[{u, v}] = ind[{v, u}] = i;
}
dfs(1);
for (int i = 0; i < m; i ++){
int x;
cin >> x;
int L = 0;
for (int j = 0; j < x; j ++){
int v;
cin >> v;
S[v].insert(i);
if (!L)
L = v;
else
L = lca(L, v);
}
a[L]++;
inside[L].insert(i);
}
dfs_ans(1);
cout << ans.size() << endl;
for (int x : ans)
cout << x << " ";
cout << endl;
}
