#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, m, k;
cin >> n >> m >> k;
vector<vector<pair<int, int>>> con(n);
for(int i = 0; i < n-1; i++) {
int a, b;
cin >> a >> b;
a--; b--;
con[a].push_back({b, i});
con[b].push_back({a, i});
}
vector<int> dep(n), order(n);
vector<vector<int>> p(20, vector<int>(n));
int id = 0;
function<void(int, int, int)> dfs = [&](int curr, int prev, int d) {
p[0][curr] = prev;
dep[curr] = d;
order[curr] = id++;
for(auto [next, trackId] : con[curr]) {
if(next == prev)
continue;
dfs(next, curr, d+1);
}
};
dfs(0, 0, 0);
for(int b = 1; b < sz(p); b++) {
for(int i = 0; i < n; i++) {
p[b][i] = p[b-1][p[b-1][i]];
}
}
auto lca = [&](int x, int y) {
for(int b = sz(p)-1; b >= 0; b--) {
if(dep[x]-dep[y] >= (1<<b))
x = p[b][x];
if(dep[y]-dep[x] >= (1<<b))
y = p[b][y];
}
if(x == y)
return x;
for(int b = sz(p)-1; b >= 0; b--) {
if(p[b][x] != p[b][y]) {
x = p[b][x];
y = p[b][y];
}
}
return p[0][x];
};
vector<int> track(n);
auto addPath = [&](int a, int b) {
track[a]++;
track[b]++;
track[lca(a,b)] -= 2;
};
while(m-->0) {
int s;
cin >> s;
vector<int> places(s);
for(int i = 0; i < s; i++) {
cin >> places[i];
places[i]--;
}
sort(all(places), [&](int a, int b) {
return order[a] < order[b];
});
for(int i = 0; i < s; i++) {
addPath(places[i], places[(i+1)%s]);
}
}
set<int> ans;
function<int(int, int)> go = [&](int curr, int prev) {
for(auto [next, trackId] : con[curr]) {
if(next == prev)
continue;
int traffic = go(next, curr);
if(traffic/2 >= k)
ans.insert(trackId);
track[curr] += traffic;
}
return track[curr];
};
go(0, 0);
cout << sz(ans) << "\n";
for(auto a : ans)
cout << a+1 << " ";
cout << "\n";
}
