#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define debug if(0)
const int mod = 1e9 + 7;
const ll infL = 1e18 + 7;
const int inf = 1e9 + 7;
const int N = 1e5 + 4, M = 20;
vector<int> V[N];
int tin[N], tout[N], depth[N], jump[N][M], pref[N];
int T = 1;
void dfs(int v, int p=0, int d=0) {
depth[v] = d+1;
tin[v] = T++;
jump[v][0] = p;
for(int u : V[v]) {
if(u != p) dfs(u, v, d+1);
}
tout[v] = T--;
}
int jmp(int x, int k) {
for(int i=0; i<M; i++) {
if((1<<i) & k) x = jump[x][i];
}
return x;
}
int lca(int a, int b) {
if(depth[a] < depth[b]) swap(a, b);
a = jmp(a, depth[a]-depth[b]);
if(a == b) return a;
for(int i=M-1; i>=0; i--) {
int xa = jump[a][i], xb = jump[b][i];
if(xa != xb) { a = xa; b = xb; }
}
return jump[a][0];
}
int ans[N];
void dfs2(int v, int p=0) {
ans[v] = pref[v];
for(int u : V[v]) {
if(u != p) {
dfs2(u, v);
ans[v] += ans[u];
}
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
int n, m, k; cin>>n>>m>>k;
vector<pair<int, int>> E;
for(int i=1; i<n; i++) {
int a, b; cin>>a>>b;
V[a].push_back(b);
V[b].push_back(a);
E.push_back({a, b});
}
dfs(1);
for(int j=1; j<M; j++) {
for(int i=1; i<=n; i++) jump[i][j] = jump[jump[i][j-1]][j-1];
}
for(int z=0; z<m; z++) {
int s; cin>>s;
vector<pair<int, int>> cc;
for(int i=0; i<s; i++) {
int a; cin>>a;
cc.push_back({tin[a], a});
}
sort(cc.begin(), cc.end());
for(int i=0; i<s; i++) {
int a = cc[i].second, b = cc[(i+1)%s].second;
// add on path (a, b) value 1
int lc = lca(a, b);
pref[a]++; pref[b]++; pref[lc]-=2;
}
}
dfs2(1);
vector<int> result;
for(int i=0; i<(n-1); i++) {
auto e = E[i];
int a = e.first, b = e.second;
if(depth[a] > depth[b]) swap(a, b);
if(ans[b] >= 2*k) result.push_back(i+1);
debug cerr<<"ans["<<b<<"] = "<<ans[b]<<"\n";
}
cout<<(int) result.size()<<"\n";
for(int x : result) cout<<x<<" ";
}
