#include<bits/stdc++.h>
#ifdef LOCAL
#include "Essentials/algo/debug.h"
#else
#define debug(...) 69
#endif
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
const int N = 1e5 + 23;
const int LOG = 23;
const ll inf = 1e18;
#define F first
#define S second
#define pb push_back
#define kill(x) cout<<x<<endl, exit(0);
#define all(x) x.begin(),x.end()
#define sz(x) (int)x.size()
#define lc (v << 1)
#define rc ((v<<1) |1)
int n,m,k;
vector<pii> G[N];
int dp[N];
int up[LOG][N];
int h[N];
int st[N],timer =0;
void dfsset(int v,int p = 1) {
up[0][v] = p;
st[v] = timer ++;
for(int i = 1; i < LOG; i ++) {
up[i][v] = up[i-1][up[i-1][v]];
}
for(auto [u,_] : G[v]) if(u != p) {
h[u] = h[v] + 1;
dfsset(u,v);
}
}
int getPar(int v,int sex) {
for(int i = 0 ;i < LOG ; i ++)
if((sex>>i)&1)
v = up[i][v];
return v;
}
int lca(int v,int u) {
if(h[v] < h[u]) swap(v,u);
v= getPar(v,h[v]-h[u]);
if(v == u) return v;
for(int i = LOG-1;i >=0 ; i --)
if(up[i][v] != up[i][u])
v = up[i][v],u = up[i][u];
return up[0][v];
}
vector<int> ans;
void dfs(int v,int p = -1,int wid=-1) {
for(auto [u,_] : G[v]) if(u != p) {
dfs(u,v,_);
dp[v] += dp[u];
}
if(wid != -1 && dp[v]/2 >= k) {
ans.pb(wid);
}
}
vector<int> sex;
int32_t main() {
cin.tie(nullptr)->sync_with_stdio(false);
cin>>n>>m>>k;
for(int i =1; i < n ; i ++) {
int v,u; cin>>v>>u;
G[v].pb({u,i});
G[u].pb({v,i});
}
dfsset(1);
while(m--) {
sex.clear();
int s; cin>>s;
for(int i = 0; i < s; i++) {
int x; cin>>x;
sex.pb(x);
}
sort(all(sex), [&] (int x,int y) {return st[x] < st[y];});
for(int i = 1; i < s; i ++) {
int v = sex[i-1],u =sex[i];
dp[v] ++,dp[u] ++;
dp[lca(v,u)] -= 2;
}
dp[sex[0]] ++,dp[sex[s-1]] ++;
dp[lca(sex[0],sex[s-1])] -= 2;
}
dfs(1);
sort(all(ans));
cout<<sz(ans) << '\n';
for(int x : ans) cout<<x << ' ';
return 0;
}
