#include<bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 5;
vector<int> g[maxn];
int h[maxn], up[maxn][22], tin[maxn], out[maxn], cost[maxn], timeDfs = 0;
map<pair<int, int>, int> mp;
void dfs(int u){
tin[u] = ++timeDfs;
for(int v: g[u]){
if(v == up[u][0]) continue;
h[v] = h[u] + 1;
up[v][0] = u;
for(int j = 1; j <= 21; j++) up[v][j] = up[up[v][j - 1]][j - 1];
dfs(v);
}
out[u] = timeDfs;
}
int lca(int u, int v){
if(h[u] != h[v]){
if(h[u] < h[v]) swap(u, v);
int k = h[u] - h[v];
for(int j = 0; (1 << j) <= k; j++){
if((k >> j) & 1){
u = up[u][j];
}
}
}
if(u == v) return u;
int k = __lg(h[u]);
for(int j = k; j >= 0; j--) {
if(up[u][j] != up[v][j]){
u = up[u][j];
v = up[v][j];
}
}
return up[u][0];
}
vector<int> vert, ans;
//dựng cây ảo
void build(){
//sắp xếp lại theo tin để thêm lca và dựng cây
sort(vert.begin(), vert.end(), [&](int c, int d) {return tin[c] < tin[d];});
int k = vert.size();
for(int i = 0; i < k - 1; i++) vert.push_back(lca(vert[i], vert[i + 1]));
//sắp xếp lại theo tin và nén
sort(vert.begin(), vert.end(), [&](int c, int d) {return tin[c] < tin[d];});
vert.erase(unique(vert.begin(), vert.end()), vert.end());
stack<int> st;
for(int u: vert) {
while(st.size() && !(tin[st.top()] <= tin[u] && tin[u] <= out[st.top()])) st.pop();
if(st.size()){
cost[st.top()]--;
cost[u]++;
}
st.push(u);
}
}
int kk;
void dfs2(int u, int pre){
for(int v: g[u]){
if(v == pre) continue;
dfs2(v, u);
cost[u] += cost[v];
}
if(cost[u] >= kk && u > 1) ans.push_back(mp[{min(u, up[u][0]), max(u, up[u][0])}]);
}
void solve(){
int n, m, k; cin >> n >> m >> k;
kk = k;
for(int i = 1; i <= n - 1; i++) {
int u, v; cin >> u >> v;
g[u].push_back(v);
g[v].push_back(u);
mp[{min(u, v), max(u, v)}] = i;
}
dfs(1);
while(m--){
int sz; cin >> sz;
vert.resize(sz);
for(int i = 0; i < sz; i++) cin >> vert[i];
build();
}
dfs2(1, 0);
cout << ans.size() << "\n";
sort(ans.begin(), ans.end());
for(int x: ans) cout << x << " ";
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
}
