#include <bits/stdc++.h>
#define IO ios::sync_with_stdio(false);cin.tie(0);
#define debug(x) cerr << #x << " = " << (x) << ' '
#define bug(x) cerr << (x) << ' '
#define endl cerr << '\n'
#define all(v) (v).begin(), (v).end()
#define SZ(v) (ll)(v).size()
#define lowbit(x) (x)&-(x)
#define pb emplace_back
#define F first
#define S second
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
//#define TEST
const int N = 1e5+5;
const int LogN = 17;
int tin[N], tout[N], timer, anc[LogN+5][N], cnt[N];
vector<pll> g[N];
vector<int> v[N], ans;
inline void dfs0(int x, int pre)
{
tin[x] = ++timer, anc[0][x] = pre;
for (auto e : g[x])
{
int v = e.F, id = e.S;
if (v == pre) continue;
dfs0(v, x);
}
tout[x] = ++timer;
}
inline bool is_anc(int x, int y)
{ return tin[x] <= tin[y] && tout[y] <= tout[x]; }
inline int get_lca(int x, int y)
{
if (is_anc(x, y)) return x;
if (is_anc(y, x)) return y;
for (int i=LogN; i >= 0; --i)
if (anc[i][x] && !is_anc(anc[i][x], y)) x = anc[i][x];
return anc[0][x];
}
inline set<int> dfs(int x, int pre)
{
set<int> st, tmp;
for (auto e : g[x])
{
int v = e.F, id = e.S;
if (v == pre) continue;
tmp = dfs(v, x);
cnt[id] = SZ(tmp);
if (SZ(st) < SZ(tmp)) swap(st, tmp);
for (int xx : tmp) st.insert(xx);
}
for (int d : v[x]) if (d > 0) st.insert(d);
for (int d : v[x]) if (d < 0) st.erase(-d);
return st;
}
int main(void)
{ IO
int n, i, Q, K;
cin >> n >> Q >> K;
for (i=1; i <= n-1; ++i)
{
int x, y; cin >> x >> y;
g[x].pb(y, i), g[y].pb(x, i);
}
dfs0(1, 0);
for (i=1; i <= LogN; ++i)
for (int j=1; j <= n; ++j) anc[i][j] = anc[i-1][anc[i-1][j]];
for (i=1; i <= Q; ++i)
{
int k, pre = 0; cin >> k;
for (int j=0; j < k; ++j)
{
int x; cin >> x;
pre = (pre)?get_lca(pre, x) : x;
v[x].pb(i);
}
v[pre].pb(-i);
}
for (i=1; i <= n; ++i)
{
sort(all(v[i]));
v[i].resize(unique(all(v[i]))-v[i].begin());
}
dfs(1, 0);
for (i=1; i <= n-1; ++i)
if (cnt[i] >= K) ans.pb(i);
cout << SZ(ans) << '\n';
for (int i : ans) cout << i << ' ';
cout << '\n';
return 0;
}
