#include <bits/stdc++.h>
using namespace std;
const int LOG = 16;
int n,m,k;
struct canh {
int u,v;
int other (const int & x) {
return u ^ v ^ x;
}
} edge[100009];
vector <int> adj[100009];
int tin[100009],timedfs;
int up[100009][LOG + 1],h[100009];
void dfs(int node,int par) {
tin[node] = ++timedfs;
for (auto x : adj[node]) {
int child = edge[x].other(node);
if (child == par) continue;
h[child] = h[node] + 1;
up[child][0] = node;
for (int i = 1;i <= LOG;i++) {
up[child][i] = up[up[child][i - 1]][i - 1];
}
dfs(child,node);
}
}
int sum[100009];
int lca(int u,int v) {
if (h[u] < h[v]) swap(u,v);
int diff = h[u] - h[v];
for (int i = LOG;i >= 0;i--) if (diff >> i & 1) u = up[u][i];
if (u == v) return u;
for (int i = LOG;i >= 0;i--) if (up[u][i] != up[v][i]) {
u = up[u][i];
v = up[v][i];
}
return up[u][0];
}
void increase(int u,int v) {
sum[u]++;
sum[v]++;
sum[lca(u,v)] -= 2;
}
vector <int> print;
void redfs(int node,int par) {
int d;
for (auto x : adj[node]) {
int child = edge[x].other(node);
if (child == par) {
d = x;
continue;
}
redfs(child,node);
sum[node] += sum[child];
}
if (sum[node] >= 2*k) print.push_back(d);
}
int main() {
ios_base::sync_with_stdio(0);cin.tie(nullptr);
//freopen(".inp","r",stdin);
//freopen(".out","w",stdout);
cin >> n >> m >> k;
for (int i = 1;i < n;i++) {
cin >> edge[i].u >> edge[i].v;
adj[edge[i].u].push_back(i);
adj[edge[i].v].push_back(i);
}
dfs(1,-1);
while (m--) {
int num;cin >> num;
vector <int> plan(num,0);
for (int i = 0;i < num;i++) cin >> plan[i];
sort(plan.begin(),plan.end(),[] (int a,int b) {
return tin[a] < tin[b];
});
plan.push_back(plan[0]);
for (int i = 1;i < plan.size();i++) {
increase(plan[i - 1],plan[i]);
}
}
redfs(1,-1);
sort(print.begin(),print.end());
cout << print.size() << '\n';
for (auto a : print) cout << a << " ";
}
/*
Nho doi vai em gay
co gai ay ngoi duoi goc pho nen tho ...
*/
