#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef pair<int, int> pi;
#define debug(x) cerr << #x << ": " << x << endl
#define debug2(x, y) debug(x), debug(y)
#define repn(i, a, b) for(int i = (int)(a); i < (int)(b); i++)
#define rep(i, a) for(int i = 0; i < (int)(a); i++)
#define all(v) v.begin(), v.end()
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define sq(x) ((x) * (x))
const int mxN = 1e5 + 5;
template<class T> T gcd(T a, T b){ return ((b == 0) ? a : gcd(b, a % b)); }
int n, m, k;
vi g[mxN];
vi st1[mxN], en[mxN];
vi ans;
vector<vi> up;
int st[mxN], fin[mxN];
int num = 0, l = 1;
void dfs(int cur, int prev = 0){
st[cur] = num++;
up[cur][0] = prev;
repn(i, 1, l + 1) up[cur][i] = up[up[cur][i - 1]][i - 1];
for(int x : g[cur]) if(x != prev) dfs(x, cur);
fin[cur] = num++;
}
bool upper(int a, int b){
return st[a] <= st[b] && fin[a] >= fin[b];
}
int lca(int a, int b){
if(upper(a, b)) return a;
if(upper(b, a)) return b;
for(int i = l; i >= 0; i--) if(!upper(up[a][i], b)) a = up[a][i];
return up[a][0];
}
map<pi, int> ind;
set<int> cnt[mxN];
void dfs1(int cur, int prev){
//merge
for(int x : g[cur]) if(x != prev){
dfs1(x, cur);
if(cnt[cur] < cnt[x]) swap(cnt[x], cnt[cur]);
for(int y : cnt[x]) cnt[cur].insert(y);
}
//add the current ones
for(int x : st1[cur]) cnt[cur].insert(x);
//delete
for(int x : en[cur]){
auto it = cnt[cur].find(x);
if(it != cnt[cur].end()) cnt[cur].erase(it);
}
if(cnt[cur].size() >= k && prev != -1) ans.pb(ind[mp(cur, prev)]);
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
//freopen("input.in", "r", stdin);
//freopen("output.out", "w", stdout);
cin >> n >> m >> k;
rep(i, n - 1){
int a, b;
cin >> a >> b;
a--, b--;
ind[mp(a, b)] = ind[mp(b, a)] = i;
g[a].pb(b);
g[b].pb(a);
}
up.resize(n + 1);
while((1 << l) <= n) l++;
rep(i, n) up[i].resize(l + 1);
dfs(0);
rep(i, m){
int s;
cin >> s;
int lc;
rep(j, s){
int x;
cin >> x;
x--;
if(!j) lc = x;
else lc = lca(lc, x);
st1[x].pb(i);
}
en[lc].pb(i);
}
dfs1(0, -1);
cout << (int)(ans.size()) << endl;
sort(all(ans));
for(int x : ans) cout << x + 1 << " ";
cout << endl;
return 0;
}
/*
Things to look out for:
- Integer overflows
- Array bounds
- Special cases
Be careful!
*/
