#include <bits/stdc++.h>
using namespace std;
#define all(x) x.begin(), x.end()
const int mxN = 1e5 + 10;
const int mxB = 21;
vector<pair<int, int>> adj[mxN];
int st[mxN], eid[mxN], va[mxN], dp[mxN][mxB], depth[mxN], tin = 0;
void dfs(int u, int par){
st[u] = ++tin, dp[u][0] = par, depth[u] = depth[par] + 1;
dp[u][0] = par;
for(int i = 1; i < mxB; ++i) dp[u][i] = dp[dp[u][i - 1]][i - 1];
for(auto it : adj[u]){
if(it.first ^ par){
eid[it.first] = it.second;
dfs(it.first, u);
}
}
}
void dfs2(int u, int par){
for(auto it : adj[u]){
if(it.first ^ par){
dfs2(it.first, u);
va[u] += va[it.first];
}
}
}
int kth(int u, int k){
for(int i = 0; i < mxB; ++i){
if(k & (1ll << i)) u = dp[u][i];
}
return u;
}
int lca(int u, int v){
if(depth[u] < depth[v]) swap(u,v);
u = kth(u, abs(depth[u] - depth[v]));
if(u == v) return u;
for(int i = mxB - 1; i >= 0; --i){
if(dp[u][i] != dp[v][i]){
u = dp[u][i];
v = dp[v][i];
}
}
return dp[u][0];
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
for(int i = 1, u, v; i <= n - 1; ++i){
cin >> u >> v;
adj[u].push_back({v, i});
adj[v].push_back({u, i});
} dfs(1, 0);
auto update = [&](int u, int v) -> void {
va[u] += 1, va[v] += 1;
va[lca(u, v)] -= 2;
// cout << lca(u, v) << " lca " << u << " " << v << "\n";
};
while(m--){
int sz; cin >> sz;
vector<int> v(sz);
for(int i = 0; i < sz; ++i) cin >> v[i];
sort(all(v), [&](int x, int y){
return st[x] < st[y];
});
v.push_back(v[0]);
for(int i = 0; i < (int) v.size() - 1; ++i){
update(v[i], v[i + 1]);
}
}
dfs2(1, 0);
vector<int> ans;
for(int i = 2; i <= n; ++i){
//cout << va[i] << " ";
if(va[i] >= 2 * k) ans.push_back(eid[i]);
} //cout << "\n";
cout << (int) ans.size() << "\n";
sort(all(ans));
for(auto it : ans) cout << it << " ";
return 0;
}
