#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "bits/debug.h"
#else
#define debug(...)
#endif
const int maxn = 1e5 + 5;
const int LG = 17;
int n, m, k;
int eu[maxn], ev[maxn];
vector<int> g[maxn];
int tin[maxn], tout[maxn], timer;
int up[maxn][LG + 1], h[maxn];
int eid[maxn];
vector<int> cand;
int c[maxn];
void pre_dfs(int u, int prev) {
tin[u] = ++timer;
for (auto v:g[u]) {
if (v == prev) continue;
h[v] = h[u] + 1;
up[v][0] = u;
for (int i = 1; i <= LG; ++i) {
up[v][i] = up[up[v][i - 1]][i - 1];
}
pre_dfs(v, u);
}
tout[u] = timer;
}
int lca(int u, int v) {
if (h[u] < h[v]) swap(u, v);
for (int i = LG; i >= 0; --i) {
if ((h[u] - h[v]) >> i & 1) u = up[u][i];
}
if (u == v) return u;
for (int i = LG; i >= 0; --i) {
if (up[u][i] != up[v][i]) u = up[u][i], v = up[v][i];
}
return up[v][0];
}
int dist(int u, int v) {
return h[u] + h[v] - 2 * h[lca(u, v)];
}
void inc(int p, int u) {
++c[u], --c[p];
}
void upd(vector<int> &ver) {
sort(ver.begin(), ver.end(), [](const int &x, const int &y) -> bool {
return tin[x] < tin[y];
});
for (int i = (int)ver.size() - 1; i > 0; --i) {
ver.push_back(lca(ver[i], ver[i - 1]));
}
sort(ver.begin(), ver.end(), [](const int &x, const int &y) -> bool {
return tin[x] < tin[y];
});
stack<int> st;
st.push(ver[0]);
auto is_anc = [&](int u, int v) {
return tin[u] <= tin[v] and tout[v] <= tout[u];
};
for (int i = 1; i < (int)ver.size(); ++i) {
while (!st.empty() and !is_anc(st.top(), ver[i])) st.pop();
if (!st.empty()) {
inc(st.top(), ver[i]);
}
st.push(ver[i]);
}
}
void dfs(int u, int prev) {
for (auto v:g[u]) {
if (v == prev) continue;
dfs(v, u);
c[u] += c[v];
}
if (c[u] >= k and eid[u]) cand.push_back(eid[u]);
}
void solve() {
cin >> n >> m >> k;
for (int i = 1; i < n; ++i) {
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
eu[i] = u, ev[i] = v;
}
pre_dfs(1, 0);
for (int i = 1; i < n; ++i) {
if (up[eu[i]][0] == ev[i]) swap(eu[i], ev[i]);
eid[ev[i]] = i;
}
for (int i = 1; i <= m; ++i) {
int sz; cin >> sz;
vector<int> ver(sz);
for (auto &j : ver) {
cin >> j;
}
upd(ver);
}
dfs(1, 0);
sort(cand.begin(), cand.end());
cout << (int)cand.size() << '\n';
for (auto i : cand) {
cout << i << " ";
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
