#include<bits/stdc++.h>
using namespace std;
using lli = long long;
const lli maxN = 1e5 + 5;
const lli LG = 17;
lli sp[LG][2 * maxN],id1[2 * maxN],lg[2 * maxN];
lli t,t1,dep[maxN],id[maxN];
lli n,k,m,u[maxN],v[maxN],s,p[maxN],val[maxN],in[maxN];
vector<lli> adj[maxN],adjvt[maxN],vtnode,st;
struct Tedge
{
lli u,v,w;
}
evt[maxN],e[maxN];
void dfs(lli u,lli par)
{
lli node = ++t1;
id1[node] = u;sp[0][++t] = node;
id[u] = node;in[u] = t;
for (lli v : adj[u])
{
if (v == par) continue;
sp[0][++t] = node;
dep[v] = dep[u] + 1;
dfs(v,u);
}
p[u] = par;
}
void pre()
{
lg[1] = 0;
for (lli i = 2;i <= t;++i) lg[i] = lg[i / 2] + 1;
for (lli j = 1;j < LG;++j)
for (lli i = 1;i <= t - (1 << j) + 1;++i)
sp[j][i] = min(sp[j - 1][i],sp[j - 1][i + (1 << (j - 1))]);
}
lli lca(lli u,lli v)
{
lli l = in[u],r = in[v];
if (l > r) swap(l,r);
lli k = lg[r - l + 1];
return id1[min(sp[k][l],sp[k][r - (1 << k) + 1])];
}
lli cost(lli u,lli v)
{
return dep[u] + dep[v] - 2 * dep[lca(u,v)];
}
void input()
{
cin >> n >> m >> k;
for (lli i = 1;i < n;++i)
{
lli u,v;
cin >> u >> v;
e[i].u = u;e[i].v = v;
adj[u].push_back(v);
adj[v].push_back(u);
}
t = t1 = 0;dep[1] = 0;
dfs(1,0);
pre();
}
bool cmp(lli x,lli y)
{
return id[x] < id[y];
}
void buildtree()
{
vtnode.clear();
sort(u + 1,u + s + 1,cmp);
vtnode.push_back(u[s]);
for (lli i = 1;i < s;++i)
{
vtnode.push_back(u[i]);
vtnode.push_back(lca(u[i],u[i + 1]));
}
sort(vtnode.begin(),vtnode.end());
auto ip = unique(vtnode.begin(),vtnode.end());
vtnode.resize(ip - vtnode.begin());
sort(vtnode.begin(),vtnode.end(),cmp);
for (lli v : vtnode) adjvt[v].clear();
st.clear();st.push_back(vtnode[0]);
val[vtnode[0]]--;
for (lli i = 1;i < vtnode.size();++i)
{
if (!st.empty() && lca(st.back(),vtnode[i]) != st.back()) st.pop_back();
adjvt[st.back()].push_back(vtnode[i]);
st.push_back(vtnode[i]);
}
for (lli i = 0;i < vtnode.size();++i)
{
val[vtnode[i]] = val[vtnode[i]] - adjvt[vtnode[i]].size() + 1;
}
}
void calc(lli u)
{
for (lli v : adj[u])
{
if (v == p[u]) continue;
calc(v);
val[u] += val[v];
}
}
void solve()
{
while (m--)
{
cin >> s;
for (lli i = 1;i <= s;++i) cin >> u[i];
buildtree();
}
calc(1);
lli cnt = 0;
for (lli i = 1;i <= n;++i)
{
lli tmp;
if (p[e[i].v] == e[i].u) tmp = val[e[i].v];
else tmp = val[e[i].u];
if (tmp >= 2) ++cnt;
}
cout << cnt << "\n";
for (lli i = 1;i <= n;++i)
{
lli tmp;
if (p[e[i].v] == e[i].u) tmp = val[e[i].v];
else tmp = val[e[i].u];
if (tmp >= 2) cout << i << " ";
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// freopen("D.inp","r",stdin);
// freopen(D.out","w",stdout);
lli t;
input();
solve();
}
