#include <bits/stdc++.h>
#define ll long long
#define ull unsigned ll
#define pb push_back
#define pa pair<int, int>
#define pall pair<ll, int>
#define fi first
#define se second
#define TASK "test"
#define Size(x) (int) x.size()
#define all(x) x.begin(), x.end()
using namespace std;
template<typename T1, typename T2> bool mini (T1 &a, T2 b) {if(a > b) a = b; else return 0; return 1;}
template<typename T1, typename T2> bool maxi (T1 &a, T2 b) {if(a < b) a = b; else return 0; return 1;}
const int MOD = 1e9 + 7;
const int LOG = 20;
const int maxn = 1e5 + 7;
const ll oo = 1e18 + 69;
int n, m, k, u, v, id[maxn], timer = 0, st[maxn], en[maxn], ex[maxn], res[maxn], edge_id[maxn];
vector<pa> g[maxn];
struct LCA {
int p[LOG][maxn], f[maxn];
void dfs(int u, int par) {
id[u] = ++timer;
p[0][u] = par;
for(auto e:g[u]) {
int v = e.fi;
if(v == par) continue;
f[v] = f[u] + 1;
dfs(v, u);
}
}
int get_lca(int u, int v) {
if(f[u] < f[v]) swap(u, v);
int k = f[u] - f[v];
for(int i = 0; i < LOG; i++)
if((k >> i) & 1) u = p[i][u];
if(u == v) return u;
for(int i = LOG - 1; i >= 0; i--)
if(p[i][u] != p[i][v]) {
u = p[i][u];
v = p[i][v];
}
return p[0][u];
}
void init() {
f[1] = 0;
dfs(1, 0);
for(int i = 1; i < LOG; i++) {
for(int u = 1; u <= n; u++) p[i][u] = p[i - 1][p[i - 1][u]];
}
}
int jump(int u, int k) {
for(int i = 0; i < LOG; i++)
if((k >> i) & 1) u = p[i][u];
return u;
}
void add(int u, int v) {
int par = get_lca(u, v);
st[u]++;
st[v]++;
en[par] += 2;
if(u != par && v != par) ex[par]++;
else {
st[par]--;
en[par]--;
}
}
void update(int u, int v) {
int par = get_lca(u, v);
if(u != par) add(u, jump(u, f[u] - f[par] - 1));
if(v != par) add(v, jump(v, f[v] - f[par] - 1));
}
} lca;
bool cmp(int a, int b) {
return id[a] < id[b];
}
void dfs(int u, int par) {
for(auto e:g[u]) {
int v = e.fi;
if(v == par) continue;
edge_id[v] = e.se;
dfs(v, u);
st[u] += st[v];
}
res[u] = st[u] - ex[u];
st[u] -= en[u];
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
//freopen(TASK".inp", "r", stdin);
//freopen(TASK".out", "w", stdout);
cin>>n>>m>>k;
for(int i = 1; i < n; i++) {
cin>>u>>v;
g[u].pb({v, i});
g[v].pb({u, i});
}
lca.init();
while(m--) {
cin>>u;
vector<int> a;
for(int i = 0; i < u; i++) {
cin>>v;
a.pb(v);
}
sort(all(a), cmp);
for(int i = 0; i < u; i++) {
int j = (i + 1) % u;
lca.update(a[i], a[j]);
}
}
dfs(1, 0);
vector<int> ans;
for(int i = 1; i <= n; i++) {
if(res[i] >= 2 * k) ans.pb(edge_id[i]);
}
cout<<Size(ans)<<"\n";
sort(all(ans));
for(auto i:ans) cout<<i<<" ";
return 0;
}
