#include <iostream>
#include <cstdio>
#include <algorithm>
#include <string.h>
#include <vector>
#include <set>
using namespace std;
#define endl '\n'
#define pi pair<int, int>
#define f first
#define s second
const int maxn = 100001;
struct BIT{
int bit[maxn];
BIT(){
memset(bit, 0, sizeof(bit));
}
void add(int x, int v){
for(x++; x < maxn; x += x & -x) bit[x] += v;
}
int qry(int x){
int ret = 0;
for(x++; x; x -= x & -x) ret += bit[x];
return ret;
}
int qry(int a, int b){
return qry(b) - qry(a - 1);
}
};
const int w = 18;
int n, m, k;
int l[maxn], r[maxn], d[maxn], dp[maxn];
int p[w][maxn];
vector<pi> graph[maxn];
BIT bit;
vector<int> ans;
auto cmp = [&](int x, int y){
return (pi){r[x], -l[x]} < (pi){r[y], -l[y]};
};
set<int, decltype(cmp)> a(cmp);
vector<pi> b;
int dfs(int c){
r[c] = l[c];
for(pi i : graph[c]){
if(i.f == p[0][c]) continue;
d[i.f] = d[c] + 1;
l[i.f] = r[c] + 1;
p[0][i.f] = c;
r[c] = dfs(i.f);
}
return r[c];
}
int lca(int x, int y){
if(d[x] < d[y]) swap(x, y);
for(int i = w - 1; i >= 0; i--) if(p[i][x] != -1 && d[p[i][x]] >= d[y]) x = p[i][x];
for(int i = w - 1; i >= 0; i--){
if(p[i][x] != p[i][y]){
x = p[i][x];
y = p[i][y];
}
}
return x == y ? x : p[0][x];
}
void dfs2(int c){
for(pi i : graph[c]){
if(i.f == p[0][c]) continue;
dfs2(i.f);
if(dp[i.f] >= k) ans.push_back(i.s);
dp[c] += dp[i.f];
}
}
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> n >> m >> k;
for(int i = 1; i < n; i++){
int u, v;
cin >> u >> v;
u--, v--;
graph[u].push_back({v, i});
graph[v].push_back({u, i});
}
p[0][0] = -1;
dfs(0);
for(int i = 1; i < w; i++)
for(int j = 0; j < n; j++){
p[i][j] = p[i - 1][j] == -1 ? -1 : p[i - 1][p[i - 1][j]];
}
for(int i = 0; i < m; i++){
int s;
cin >> s;
b.clear();
for(int j = 0; j < s; j++){
int x;
cin >> x;
x--;
a.insert(x);
}
while(!a.empty()){
if(!b.empty()) a.insert(lca(b.back().f, *a.begin()));
b.push_back({*a.begin(), 0});
a.erase(a.begin());
b.back().s = -bit.qry(l[b.back().f], r[b.back().f]) + 1;
bit.add(l[b.back().f], b.back().s);
dp[b.back().f] += b.back().s;
}
dp[b.back().f]--;
for(pi i : b){
bit.add(l[i.f], -i.s);
}
}
dfs2(0);
sort(ans.begin(), ans.end());
cout << ans.size() << endl;
if(!ans.empty()) cout << ans[0];
for(int i = 1; i < ans.size(); i++) cout << " " << ans[i];
cout << endl;
return 0;
}
