#include <bits/stdc++.h>
#define all(v) begin(v), end(v)
using namespace std;
const int MAXN = 1e5 + 5;
struct edge{
int u, v;
edge(int _u = 0, int _v = 0): u(_u), v(_v) {};
int other(int x){
return u ^ v ^ x;
}
};
int numNode, numQuery, numReq, sta[MAXN], fin[MAXN], dp[MAXN], chain[MAXN], par[MAXN], sz[MAXN], cnt[MAXN], h[MAXN];
vector<int> adj[MAXN];
edge e[MAXN];
void dfsInit(int u){
sz[u] = 1;
for(int id: adj[u]) if (e[id].other(u) != par[u]) {
int v = e[id].other(u); par[v] = u;
dfsInit(v);
sz[u] += sz[v];
}
sort(all(adj[u]), [&](const int &idA, const int &idB){
int a = e[idA].other(u);
int b = e[idB].other(u);
return (a == par[u] ? INT_MIN: sz[a]) > (b == par[u] ? INT_MIN: sz[b]);
});
}
void dfs(int u, bool isHeavy = 0){
chain[u] = (isHeavy ? chain[par[u]]: u);
sta[u] = ++sta[0];
for(int id: adj[u]) if (e[id].other(u) != par[u]){
int v = e[id].other(u); h[v] = h[u] + 1;
dfs(v, id == adj[u][0]);
}
fin[u] = sta[0];
}
int lca(int u, int v){
while(chain[u] != chain[v]){
int up = par[chain[u]], vp = par[chain[v]];
if (up == vp) u = up, v = vp;
else if (h[up] < h[vp]) v = vp;
else u = up;
}
return (h[u] < h[v] ? u: v);
}
void update(int u, int v){
int p = lca(u, v);
dp[u]++; dp[v]++; dp[p] -= 2;
}
void dfsGet(int u){
for(int id: adj[u]) if (e[id].other(u) != par[u]){
int v = e[id].other(u);
dfsGet(v);
dp[u] += dp[v];
cnt[id] += dp[v];
}
}
void input(){
cin >> numNode >> numQuery >> numReq;
int u, v;
for(int i = 1; i < numNode; i++){
cin >> u >> v;
adj[u].push_back(i);
adj[v].push_back(i);
e[i] = {u, v};
}
}
void solve(){
h[0] = -1;
dfsInit(1);
dfs(1);
while(numQuery--){
int numCan; cin >> numCan;
vector<int> can;
for(int i = 1; i <= numCan; i++){
int x; cin >> x;
can.push_back(x);
}
sort(all(can), [&](const int &a, const int &b){
return sta[a] < sta[b];
});
for(int i = 0; i < (int)can.size(); i++){
update(can[i], can[(i + 1) % numCan]);
}
}
dfsGet(1);
vector<int> ans;
for(int i = 1; i < numNode; i++) if (cnt[i] >= 2 * numReq){
ans.push_back(i);
}
cout << (int)ans.size() << '\n';
for(int x: ans) cout << x << ' '; cout << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if (fopen("test.inp", "r")){
freopen("test.inp", "r", stdin);
freopen("test.out", "w", stdout);
}
input();
solve();
}
