#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define ff first
#define ss second
#define pii pair<int, int>
#define sz(v) (int)(v).size()
#define all(v) (v).begin(), (v).end()
int k, tim;
vector<int> d, tin, tout, ans;
vector<vector<int>> v, u, sp;
vector<vector<pii>> E;
void dfs(int x, int pr) {
sp[x][0] = pr;
tin[x] = ++tim;
if (~pr) d[x] = d[pr] + 1;
for (auto [i, w] : E[x])
if (i != pr) dfs(i, x);
tout[x] = ++tim;
}
int lca(int x, int y) {
if (d[x] < d[y]) swap(x, y);
for (int i = 19; i >= 0; i--)
if (d[x] - (1 << i) >= d[y]) x = sp[x][i];
if (x == y) return x;
for (int i = 19; i >= 0; i--) {
if (sp[x][i] != sp[y][i]) {
x = sp[x][i]; y = sp[y][i];
}
}
return sp[x][0];
}
set<int> dfs1(int x, int pr) {
set<int> s(all(v[x]));
for (auto [i, ind] : E[x]) {
if (i != pr) {
set<int> c = dfs1(i, x);
if (k <= sz(c)) ans.push_back(ind);
if (sz(s) < sz(c)) swap(s, c);
for (auto j : c)
s.insert(j);
}
}
for (auto i : u[x])
s.erase(i);
return s;
}
int main() {
ios::sync_with_stdio(false); cin.tie(nullptr);
int n, m;
cin >> n >> m >> k;
E.assign(n, {});
for (int i = 1; i < n; i++) {
int x, y;
cin >> x >> y; x--; y--;
E[x].push_back({y, i});
E[y].push_back({x, i});
}
d = tin = tout = vector<int>(n);
sp.assign(n, vector<int>(20, -1));
dfs(0, -1);
for (int i = 1; i < 20; i++) {
for (int j = 0; j < n; j++)
if (~sp[j][i - 1]) sp[j][i] = sp[sp[j][i - 1]][i - 1];
}
v.assign(n, {});
u = v;
for (int ii = 0; ii < m; ii++) {
int z;
cin >> z;
int lc = 0;
set<pii> s;
vector<int> a(z);
for (int i = 0; i < z; i++) {
cin >> a[i]; a[i]--;
lc = (i ? lca(lc, a[i]) : a[i]);
s.insert({tin[a[i]], tout[a[i]]});
}
u[lc].push_back(ii);
for (auto i : a) {
auto t = s.lower_bound({tin[i] + 1, 0});
if (t != s.end() && (*t).ss < tout[i]) continue;
v[i].push_back(ii);
}
}
dfs1(0, -1);
sort(all(ans));
cout << sz(ans) << '\n';
for (auto i : ans)
cout << i << ' ';
}
