#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using ordered_set = tree<T,null_type,less_equal<T>,rb_tree_tag,
tree_order_statistics_node_update>;
#define ll long long
#define pi pair<int,int>
#define vi vector<int>
#define pb push_back
#define all(a) a.begin(),a.end()
const int mxn = 1e5+10, lg2 = 17;
vector<pi> g[mxn]; int qu[mxn];
int suc[mxn][lg2], val[mxn];
int tin[mxn], tout[mxn], tim;
struct BIT{
int st[mxn],sz;
void init(int n){
sz = n;
}
void add(int i, int val){
for(; i <= sz; i+=i&-i) st[i] += val;
}
int query(int l, int r){
int res = 0;
for(; r > 0; r -= r&-r) res += st[r];
for(l--; l > 0; l -= l&-l) res -= st[l];
return res;
}
}bit;
void dfs(int u, int p){
tin[u] = ++tim;
suc[u][0] = p;
for(int i = 1; i < lg2; i++) suc[u][i] = suc[suc[u][i-1]][i-1];
for(auto [v,i] : g[u]) if(v!=p){
val[v] = i;
dfs(v,u);
}
tout[u] = tim;
}
bool isanc(int u, int v){
return tin[u] <= tin[v] && tout[v] <= tout[u];
}
int getlca(int u, int v){
if(isanc(u,v)) return u;
if(isanc(v,u)) return v;
for(int i = lg2-1; i >= 0; i--)
if(!isanc(suc[u][i],v)) u = suc[u][i];
return suc[u][0];
}
void solve(){
int n,q,k; cin >> n >> q >> k;
for(int i = 1; i < n; i++){
int u,v; cin >> u >> v;
g[u].pb({v,i}); g[v].pb({u,i});
}
dfs(1,1);
bit.init(n);
while(q--){
int m; cin >> m;
for(int i = 0; i < m; i++) cin >> qu[i];
sort(qu,qu+m,[&](const int a, const int b) -> bool{
return tin[a] < tin[b];
});
qu[m] = qu[0];
for(int i = 0; i < m; i++){
bit.add(tin[qu[i]],1);
bit.add(tin[qu[i+1]],1);
bit.add(tin[getlca(qu[i],qu[i+1])],-2);
}
}
vector<int> ans;
for(int i = 2; i <= n; i++) if(bit.query(tin[i],tout[i]) >= 2*k) ans.pb(val[i]);
cout << ans.size() << '\n';
for(auto x : ans) cout << x << ' ';
}
int main(){
int t = 1;
while(t--) solve();
}
