#include <bits/stdc++.h>
using namespace std;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef long long ll;
typedef pair<ll,ll> pll;
typedef tuple<int,int,int> ti;
typedef unsigned long long ull;
typedef long double ld;
typedef vector<ll> vll;
typedef pair<ld,ld> pld;
#define pb push_back
#define popb pop_back()
#define pf push_front
#define popf pop_front
#define ff first
#define ss second
#define MOD (ll)(1000000007)
#define INF (ll) (1e18)
#define all(v) (v).begin(),(v).end()
const int nx[8] = {0, 0, 1, -1,1,1,-1,-1}, ny[8] = {1, -1, 0, 0,1,-1,1,-1}; //East, West, South, North+
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;}
ll lcm(ll a, ll b){return (a / gcd(a, b)) * b;}
////////////******SOLUTION******\\\\\\\\\\\
const int MAX_N = 2e5 + 4;;
int n, m, k, sz = 1;
vi adj[MAX_N];
int heavy[MAX_N];
vi st, lazy;
int p[MAX_N];
int head[MAX_N];
int subtree[MAX_N];
int d[MAX_N];
int eul[MAX_N];
int cur_eul = -1;
map<pii,int> key;
bool comp(int a, int b)
{
return eul[a] < eul[b];
}
void propagate(int p, int l, int r)
{
if(lazy[p] != 0)
{
st[p] += lazy[p] * (r-l+1);
if(l != r)
{
lazy[2*p] += lazy[p];
lazy[2*p+1] += lazy[p];
}
lazy[p] = 0;
}
}
int query(int p, int l, int r, int i, int j)
{
propagate(p,l,r);
if( i > j)
return 0;
if(l >= i && r <= j)
return st[p];
int mid = (l+r)/2;
return query(2*p,l,mid,i,min(mid,j))
+ query(2*p+1,mid+1,r,max(i,mid+1),j);
}
void update(int p, int l, int r, int i, int j, int val)
{
propagate(p,l,r);
if(i > j )
return ;
if(l >= i && r <= j)
{
lazy[p] += val;
propagate(p,l,r);
}
else
{
int mid = (l+r)/2;
update(2*p,l,mid,i,min(j,mid),val);
update(2*p+1,mid+1,r,max(i,mid+1),j,val);
int lsubtree = (lazy[2*p] * (r-l+1))/2 + st[2*p];
int rsubtree = (lazy[2*p+1] * (r-l+1))/2 + st[2*p+1];
st[p] = lsubtree + rsubtree;
}
}
void dfs(int x, int par)
{
d[x] = d[par] + 1;
p[x] = par;
subtree[x] = 1;
for(auto e: adj[x])
{
if(e == par) continue;
dfs(e,x);
subtree[x] += subtree[e];
if(subtree[e] > subtree[heavy[x]])
heavy[x] = e;
}
}
void decompose(int x, int h)
{
head[x] = h;
eul[x] = ++cur_eul;
if(heavy[x] != 0)
decompose(heavy[x],h);
for(auto e: adj[x])
{
if(e != p[x] && e != heavy[x])
{
decompose(e,e);
}
}
}
void upd(int a, int b)
{
for(;head[a] != head[b]; b = p[head[b]])
{
if(d[head[a]] > d[head[b]])
swap(a,b);
update(1,0,sz-1,eul[head[b]],eul[b],1);
}
if(d[a] > d[b])
swap(a,b);
update(1,0,sz-1,eul[a]+1,eul[b],1);
return ;
}
void solve()
{
cin >> n >> m >> k;
while(sz < n) sz = (sz << 1);
st.assign(2*sz+1,0);
lazy.assign(2*sz+1,0);
for(int i = 1; i <n; i ++)
{
int a,b;
cin >> a >> b;
adj[a].pb(b);
adj[b].pb(a);
key[{a,b}] = key[{b,a}] = i;
}
d[0] = -1;
dfs(1,0);
decompose(1,1);
for(int i = 1; i<= m; i ++)
{
int s; cin >> s;
int nodes[s];
for(int j = 0; j <s; j ++)
cin >> nodes[j];
sort(nodes,nodes+s,comp);
for(int j = 0; j <s; j ++)
{
int u =nodes[j];
int v = nodes[(j+1)%s];
upd(u,v);
}
}
vi ans;
for(int i= 2; i <=n; i ++)
{
int val = query(1,0,sz-1,eul[i],eul[i]);
if(val >= 2*k)
{
ans.pb(key[{i,p[i]}]);
}
}
sort(all(ans));
cout << ans.size() << '\n';
for(auto e: ans)
cout << e << ' ';
}
int main()
{
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int tt =1;
while(tt--)
{
solve();
}
}
/*
*/
