#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ll mask){return __builtin_ctzll(mask);}
int logOf(ll mask){return 63 - __builtin_clzll(mask);}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, char separator = ' ', char finish = '\n'){
for(auto item: container) cout << item << separator;
cout << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const long N = 1e5 + 69;
const long LOG_N = 17;
long n, m, k;
map<pair<long, long>, long> mp;
vector<long> graph[N];
long sum[N];
long h[N], parent[N][LOG_N], in[N], pos[N];
long dfs_cnt = 0;
void dfs(long u, long p){
in[u] = ++dfs_cnt; pos[dfs_cnt] = u;
h[u] = (u == p) ? 1 : (h[p] + 1);
for(long j = 1; MASK(j) < h[u]; ++j) parent[u][j] = parent[parent[u][j-1]][j-1];
for(long v: graph[u]) if (v != p){
parent[v][0] = u;
dfs(v, u);
}
}
long LCA(long u, long v){
if (h[u] < h[v]) swap(u, v);
long diff = h[u] - h[v];
for(long j = 0; j<LOG_N; ++j) if (GETBIT(diff, j)) u = parent[u][j];
if (u == v) return u;
for(long j = LOG_N - 1; j>=0; --j) if (parent[u][j] != parent[v][j]){
u = parent[u][j]; v = parent[v][j];
}
return parent[u][0];
}
vector<long> ans;
void calc(long u, long p){
for(long v: graph[u]) if (v != p){
calc(v, u);
sum[u] += sum[v];
if (sum[v] >= k){
long x = u, y = v;
if (x > y) swap(x, y);
ans.push_back(mp[{x, y}]);
}
}
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m >> k;
for(long i = 1; i<n; ++i){
long u, v; cin >> u >> v;
if (u > v) swap(u, v);
graph[u].push_back(v);
graph[v].push_back(u);
mp[{u, v}] = i;
}
dfs(1, 1);
while(m--){
long s; cin >> s;
vector<long> ver(s);
for(long i = 0; i<s; ++i){
cin >> ver[i];
ver[i] = in[ver[i]];
}
remove_dup(ver);
s = ver.size();
for(long i = 1; i < s; ++i) ver.push_back(in[ LCA(pos[ver[i-1]], pos[ver[i]]) ]);
remove_dup(ver);
for(long &i: ver) i = pos[i];
reverse(ALL(ver));
vector<long> st;
for(long u: ver){
while(st.size()){
long v = st.back();
if (LCA(u, v) == u){
sum[u]--;
sum[v]++;
st.pop_back();
continue;
}
else break;
}
st.push_back(u);
}
}
calc(1, 1);
cout << ans.size() << "\n";
sort(ALL(ans));
printArr(ans);
return 0;
}
