#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, m, k; cin >> n >> m >> k;
vector<vector<pair<int,int>>> adj(n);
for (int i = 1; i < n; i++){
int a, b; cin >> a >> b;
a--, b--;
adj[a].push_back({b, i});
adj[b].push_back({a, i});
}
int depth[n];
int up[n][20];
int edge[n];
int time[n];
int timer = 0;
fill(depth, depth+n, 0);
fill(edge, edge+n, -1);
function<void(int,int)> dfs = [&](int x, int prev){
up[x][0] = prev;
time[x] = timer++;
for (auto nxt : adj[x]){
if (nxt.first == prev) continue;
edge[nxt.first] = nxt.second;
depth[nxt.first] = depth[x]+1;
dfs(nxt.first, x);
}
};
dfs(0, -1);
for (int j = 1; j < 20; j++){
for (int i = 0; i < n; i++){
up[i][j] = up[i][j-1] == -1 ? -1 : up[up[i][j-1]][j-1];
}
}
function<int(int,int)> lca = [&](int a, int b){
if (depth[a]<depth[b]) swap(a,b);
for (int i = 0; i < 20; i++){
if ((1<<i)&(depth[a]-depth[b])) a = up[a][i];
}
if (a == b) return a;
for (int i = 19; i > -1; i--){
if (up[a][i] != up[b][i]){
a = up[a][i];
b = up[b][i];
}
}
return up[a][0];
};
int add[n];
int val[n];
for (int i = 0; i < n; i++) add[i] = val[i] = 0;
for (int i = 0; i < m; i++){
int s; cin >> s;
int r[s];
for (int i = 0; i < s; i++) cin >> r[i], r[i]--;
sort(r, r+s, [&](int x, int y){ return time[x] < time[y]; });
for (int i = 0; i < s; i++){
int a = r[i], b = r[(i+1)%s];
int c = lca(a, b);
add[c] -= 2;
val[a]++;
val[b]++;
}
}
int current = 0;
function<void(int,int)> dfs2 = [&](int x, int prev){
for (auto nxt : adj[x]){
if (nxt.first == prev) continue;
dfs2(nxt.first, x);
val[x] += val[nxt.first];
}
val[x] += add[x];
};
dfs2(0, -1);
vector<int> v;
for (int i = 0; i < n; i++){
if (val[i] >= 2*k){
v.push_back(edge[i]);
}
}
cout << v.size() << endl;
for (int x : v) cout << x << " ";
cout << endl;
}
