#include "bits/stdc++.h"
using namespace std;
#define rep(i,a,b) for(int i=(a); i<(b); ++i)
#define all(x) x.begin(),x.end()
#define sz(x) int(x.size())
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;
int main(){
cin.tie(NULL),cin.sync_with_stdio(false);
int n,m,k; cin >> n >> m >> k;
int B = __lg(n+1)+2;
vector<vector<array<int,2>>> adj(n);
vvi par(B+1, vi(n));
vi d(n), ord(n), cnt(n), vis(n), E(n);
int cc = 0;
auto dfs = [&](int at, int dep, auto&& dfs) -> void {
ord[at] = cc++;
vis[at] = 1;
d[at] = dep;
for(auto [to,id] : adj[at]) if (!vis[to]){
par[0][to] = at;
E[to] = id;
dfs(to,dep+1,dfs);
}
};
rep(i,0,n-1){
int u,v; cin >> u >> v;
u--,v--;
adj[u].push_back({v,i+1});
adj[v].push_back({u,i+1});
}
dfs(0,0,dfs);
rep(i,0,B) rep(j,0,n) par[i+1][j] = par[i][par[i][j]];
auto jmp = [&](int at, int k) -> int {
for(int i = 0; k; ++i, k/=2)
if(k&1) at = par[i][at];
return at;
};
auto lca = [&](int u, int v) -> int {
if (d[u] < d[v]) swap(u,v);
u = jmp(u,d[u]-d[v]);
if (u==v) return u;
for(int i = B; i>=0; --i)
if (par[i][u] != par[i][v])
u = par[i][u], v = par[i][v];
return par[0][u];
};
while (m--){
int t; cin >> t;
vi a(t);
rep(i,0,t) cin >> a[i], a[i]--;
sort(all(a),[&](int u, int v){
return ord[u] < ord[v];
});
int last = a[t-1];
for(auto cur : a){
cnt[cur]++;
cnt[last]++;
cnt[lca(cur,last)]-=2;
last = cur;
}
}
fill(all(vis),0);
auto prop = [&](int at, auto&& prop) -> void {
vis[at] = 1;
for(auto [to,id] : adj[at]) if (!vis[to]){
prop(to,prop);
cnt[at] += cnt[to];
}
};
prop(0,prop);
vi ans;
rep(i,0,n) if (cnt[i] >= 2*k) ans.push_back(E[i]);
sort(all(ans));
cout << sz(ans) << '\n';
for(auto c : ans) cout << c << ' ';
cout << '\n';
}
/*
10 3 2
1 2
2 3
3 4
4 5
5 6
6 7
7 8
1 9
9 10
5 2 5 4 6 8
6 1 3 5 6 4 10
3 1 5 7
*/
