#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename T, typename U> using ordered_map = tree<T, U, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef string str;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef vector<str> vstr;
#define FOR(i,j,k,in) for(int i=(j); i < (k);i+=in)
#define FORD(i,j,k,in) for(int i=(j); i >=(k);i-=in)
#define REP(i,b) FOR(i,0,b,1)
#define REPD(i,b) FORD(i,b,0,1)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(x) begin(x), end(x)
#define rsz resize
#define MANY_TESTS int tcase; cin >> tcase; while(tcase--)
const double EPS = 1e-9;
const int MOD = 1e9+7; // 998244353;
const ll INFF = 1e18;
const int INF = 1e9;
const ld PI = acos((ld)-1);
const vi dy = {1, 0, -1, 0, -1, 1, 1, -1};
const vi dx = {0, 1, 0, -1, -1, 1, -1, 1};
#ifdef DEBUG
#define DBG if(1)
#else
#define DBG if(0)
#endif
#define dbg(x) cout << "(" << #x << " : " << x << ")" << endl;
// ostreams
template <class T, class U>
ostream& operator<<(ostream& out, const pair<T, U> &par) {out << "[" << par.first << ";" << par.second << "]"; return out;}
template <class T>
ostream& operator<<(ostream& out, const set<T> &cont) { out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template <class T, class U>
ostream& operator<<(ostream& out, const map<T, U> &cont) {out << "{"; for( const auto &x:cont) out << x << ", "; out << "}"; return out; }
template<class T>
ostream& operator<<(ostream& out, const vector<T> &v){ out << "["; REP(i, v.size()) out << v[i] << ", "; out << "]"; return out;}
// istreams
template<class T>
istream& operator>>(istream& in, vector<T> &v){ for(auto &x : v) in >> x; return in; }
template<class T, class U>
istream& operator>>(istream& in, pair<T, U> &p){ in >> p.ff >> p.ss; return in; }
//searches
template<typename T, typename U>
T bsl(T lo, T hi, U f){ hi++; T mid; while(lo < hi){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid+1; } return lo; }
template<typename U>
double bsld(double lo, double hi, U f, double p = 1e-9){ int r = 3 + (int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? hi = mid : lo = mid; } return (lo + hi)/2; }
template<typename T, typename U>
T bsh(T lo, T hi, U f){ lo--; T mid; while(lo < hi){ mid = (lo + hi + 1)/2; f(mid) ? lo = mid : hi = mid-1; } return lo; }
template<typename U>
double bshd(double lo, double hi, U f, double p = 1e-9){ int r = 3+(int)log2((hi - lo)/p); double mid; while(r--){ mid = (lo + hi)/2; f(mid) ? lo = mid : hi = mid; } return (lo + hi)/2; }
// some more utility functions
template<typename T>
pair<T, int> get_min(vector<T> &v){ typename vector<T> :: iterator it = min_element(v.begin(), v.end()); return mp(*it, it - v.begin());}
template<typename T>
pair<T, int> get_max(vector<T> &v){ typename vector<T> :: iterator it = max_element(v.begin(), v.end()); return mp(*it, it - v.begin());}
template<typename T> bool ckmin(T& a, const T& b){return b < a ? a = b , true : false;}
template<typename T> bool ckmax(T& a, const T& b){return b > a ? a = b, true : false;}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int n, m, k;
cin >> n >> m >> k;
vector<vector<array<int, 2>>> g(n);
vector<int> ans(n - 1, 0); // how many times is the edge requested
REP(i, n -1){
int u, v;
cin >> u >> v;
u--; v--;
g[u].pb({v, i});
g[v].pb({u, i});
}
const int mx = 19;
vector<vector<int>> nxt(n, vector<int>(mx, -1));
vector<int> lev(n, 0);
vector<int> in(n);
vector<int> out(n);
int t = 0;
function<void(int, int)> dfs = [&](int v, int p){
in[v] = t; t++;
if(p != -1)
lev[v] = lev[p] + 1;
nxt[v][0] = p;
FOR(i, 1, mx, 1){
if(nxt[v][i - 1] != -1){
nxt[v][i] = nxt[nxt[v][i - 1]][i - 1];
}
}
for(auto x : g[v]){
if(x[0] == p) continue;
dfs(x[0], v);
}
out[v] = t;
};
dfs(0, -1);
auto lca = [&](int u, int v){
if(lev[u] < lev[v]) swap(u, v);
REPD(i, mx - 1){
if(lev[u] - (1 << i) >= lev[v])
u = nxt[u][i];
}
if(u == v) return u;
REPD(i, mx - 1){
if(nxt[u][i] != nxt[v][i]){
u = nxt[u][i];
v = nxt[v][i];
}
}
return nxt[u][0];
};
vector<vector<int>> vg(n);
auto build_virtual_tree = [&](vector<int> &vert){
auto cmp = [&](int u, int v){
return in[u] < in[v];
};
auto upper = [&](int u, int v){
return (in[u] <= in[v] && out[u] >= out[v]);
};
sort(all(vert), cmp);
int up = (int)vert.size() - 1;
REP(i, up){
vert.pb(lca(vert[i], vert[i + 1]));
}
sort(all(vert), cmp);
vert.erase(unique(all(vert)), vert.end());
for(int x : vert)
vg[x].clear();
vector<int> st;
st.pb(vert[0]);
FOR(i, 1, vert.size(), 1){
while(st.size() >= 2 && !upper(st.back(), vert[i])){
int u = st[(int)st.size() - 1]; int v = st[(int)st.size() - 2];
vg[u].pb(v);
vg[v].pb(u);
st.pop_back();
}
st.push_back(vert[i]);
}
while(st.size() >= 2){
int u = st[(int)st.size() - 1]; int v = st[(int)st.size() - 2];
vg[u].pb(v);
vg[v].pb(u);
st.pop_back();
}
return st[0];
};
vector<int> lazy(n, 0);
auto add_on_path = [&](int u, int v){
lazy[u]++; lazy[v]++;
lazy[lca(u, v)]-=2;
};
auto propagate_lazy = [&](){
vector<int> st;
queue<int> q;
q.push(0); st.push_back(0);
vector<bool> visited(n, false);
visited[0] = true;
while(!q.empty()){
int v = q.front();
q.pop();
for(auto x : g[v]){
if(!visited[x[0]]){
visited[x[0]] = true;
q.push(x[0]);
st.push_back(x[0]);
}
}
}
while(!st.empty()){
int v = st.back();
st.pop_back();
int par = nxt[v][0];
lazy[par] += lazy[v];
for(auto x : g[v]){
if(x[0] == par)
ans[x[1]] += lazy[v];
}
}
};
vector<int> vert;
REP(i, m){
int ns; cin >> ns;
vert.clear();
REP(j, ns){
int s; cin >> s;
s--;
vert.pb(s);
}
int root = build_virtual_tree(vert);
function<void(int, int)> go = [&](int v, int p){
for(int x : vg[v]){
if(x == p) continue;
add_on_path(v, x);
go(x, v);
}
};
go(root, -1);
}
propagate_lazy();
vector<int> res;
REP(i, n - 1){
if(ans[i] >= k)
res.pb(i);
}
cout << res.size() << "\n";
REP(j, res.size()){
cout << res[j] + 1 << (j == (int)res.size() - 1 ? "\n" : " ");
}
return 0;
}
