#include <bits/stdc++.h>
#define int long long
#define taskname "main"
#define debug(a, l, r) for (int _i = (l); _i <= (r); _i++) cout<<(a)[_i]<<' '; cout<<'\n';
using namespace std;
const int
maxN = 1e5,
maxLg = 20;
int n, m, k, disc,
h[maxN + 5],
idx_e[maxN + 5], // idx_e cua node u
cnt_use[maxN + 5],
up[maxN + 5][maxLg + 5];
vector <int>
w[maxN + 5],
suit_city;
struct Edge
{
int u, v;
void read()
{
cin >> u >> v;
}
void print()
{
cout << u << ' ' << v << '\n';
}
}; vector <Edge> list_e;
struct Range
{
int l, r;
} lim[maxN + 5];
struct FenTree
{
int bit[maxN + 1];
private:
int get(int u)
{
int res = 0;
for (int i = u; i > 0; i -= i & -i)
res += bit[i];
return res;
}
public:
void upd(int u, int x)
{
for (int i = u; i <= maxN; i += i & -i)
bit[i] += x;
}
int get_r(int l, int r)
{
return get(r) - get(l - 1);
}
} ft;
void init()
{
cin >> n >> m >> k;
for (int i = 1; i < n; i++)
{
int u, v; cin >> u >> v;
w[u].push_back(v);
w[v].push_back(u);
list_e.push_back({u, v});
}
}
void dfs(int u, int pre)
{
lim[u].l = ++disc;
for (int v: w[u])
{
if (v != pre)
{
h[v] = h[u] + 1;
up[v][0] = u;
for (int deg = 1; deg <= maxLg; deg++)
up[v][deg] = up[up[v][deg - 1]][deg - 1];
dfs(v, u);
}
}
lim[u].r = disc;
}
int lift(int u, int x)
{
for (int i = maxLg; i >= 0; i--)
if (x >> i & 1)
u = up[u][i];
return u;
}
int lca(int u, int v)
{
if (h[u] > h[v])
swap(u, v);
v = lift(v, h[v] - h[u]);
if (u == v)
return u;
for (int i = maxLg; i >= 0; i--)
{
if (up[u][i] != up[v][i])
{
u = up[u][i];
v = up[v][i];
}
}
return up[u][0];
}
void make_virt(int sz)
{
stack <int> st;
for (int i = 1; i < sz; i++)
suit_city.push_back(lca(suit_city[i], suit_city[i - 1]));
sort(suit_city.begin(), suit_city.end(), [](int x, int y){
return lim[x].l < lim[y].l;
});
suit_city.erase(unique(suit_city.begin(), suit_city.end()), suit_city.end());
for (int u: suit_city)
{
if (st.empty())
{
st.push(u);
continue;
}
while (lift(u, h[u] - h[st.top()]) != st.top())
st.pop();
list_e.push_back({st.top(), u});
st.push(u);
}
}
void set_idxe()
{
dfs(1, 0);
for (int i = 0; i < list_e.size(); i++)
{
Edge e = list_e[i];
if (lim[e.u].l > lim[e.v].l)
swap(e.u, e.v);
idx_e[e.v] = i + 1;
}
list_e.clear();
}
void add_eval()
{
for (int i = 1; i <= m; i++)
{
int sz; cin >> sz;
for (int i = 1; i <= sz; i++)
{
int u; cin >> u;
suit_city.push_back(u);
}
make_virt(sz);
suit_city.clear();
}
}
void upd_path(int u, int v)
{
if (h[u] > h[v])
swap(u, v);
ft.upd(lim[v].l, 1);
ft.upd(lim[u].l, -1);
}
void solve()
{
for (Edge e: list_e)
upd_path(e.u, e.v);
suit_city.clear();
for (int i = 1; i <= n; i++)
{
if (ft.get_r(lim[i].l, lim[i].r) >= k)
suit_city.push_back(i);
}
cout << suit_city.size() << '\n';
for (int u: suit_city)
cout << idx_e[u] << ' ';
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
if (fopen(taskname".inp", "r"))
{
freopen(taskname".inp", "r", stdin);
freopen(taskname".out", "w", stdout);
}
init(); set_idxe(); add_eval(); solve();
}
