#include <bits/stdc++.h>
using namespace std;
const int MXN = 100 * 1000 + 3;
const int LGN = 19;
vector<int> g[MXN];
int nxt[MXN], up[MXN][LGN], dt[MXN], tin[MXN], p[MXN];
int n, m, k;
void dfs(int v = 1, int pp = 1) {
up[v][0] = pp;
tin[v] = ++tin[0];
for(int i = 1; i < LGN; ++i)
up[v][i] = up[up[v][i - 1]][i - 1];
for(int u : g[v]) if(u != pp) {
dt[u] = dt[v] + 1;
dfs(u, v);
}
}
int kth(int v, int diff) {
for(int i = 0; i < LGN; i++)
if(diff >> i & 1)
v = up[v][i];
return v;
}
int LCA(int u, int v) {
if(dt[u] > dt[v])
swap(u, v);
v = kth(v, dt[v] - dt[u]);
if(u == v)
return u;
for(int i = LGN - 1; i >= 0; i--)
if(up[u][i] != up[v][i])
u = up[u][i], v = up[v][i];
return up[u][0];
}
int init(int v = 1, int pp = -1) {
for(int u : g[v]) if(u != pp)
p[v] += init(u, v);
return p[v];
}
signed main() {
std::ios::sync_with_stdio(0);
std::cout.tie(0);
std::cin.tie(0);
#ifdef saarang
freopen("/home/saarang/Documents/code/input.txt", "r", stdin);
freopen("/home/saarang/Documents/code/output.txt", "w", stdout);
#endif
cin >> n >> m >> k;
vector<array<int, 2>> ed(n - 1);
for(auto &[u, v] : ed) {
cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
}
dfs();
for(int i = 0; i < n - 1; i++) {
if(dt[ed[i][0]] < dt[ed[i][1]])
swap(ed[i][0], ed[i][1]);
nxt[ed[i][0]] = i + 1;
}
while(m--) {
int s; cin >> s;
vector<int> a(s);
for(int &x : a)
cin >> x;
sort(a.begin(), a.end(), [&] (int i, int j) {
return tin[i] < tin[j];
});
a.push_back(a[0]);
for(int i = 0; i < s; i++) {
p[a[i]]++;
p[a[i + 1]]++;
p[LCA(a[i], a[i + 1])] -= 2;
}
}
init();
vector<int> answer;
for(int i = 1; i <= n; i++)
if(p[i] >= 2 * k)
answer.push_back(nxt[i]);
sort(answer.begin(), answer.end());
cout << answer.size() << '\n';
for(int id : answer)
cout << id << ' ';
cout << '\n';
return 0;
}
