#include <bits/stdc++.h>
using namespace std;
const int N = 1e5+4, lg = 17;
int tin[N], tout[N], t, up[lg][N], p[N][2], a[N], s[N], k;
vector<int> ans;
vector<array<int,2>> e[N];
void dfs(int c)
{
tin[c]=++t;
up[0][c]=p[c][0];
for (int i=1;i<lg;++i)
up[i][c]=up[i-1][up[i-1][c]];
for (auto i : e[c])
if (i[0]!=p[c][0])
{
p[i[0]][0]=c;
p[i[0]][1]=i[1];
dfs(i[0]);
}
tout[c]=++t;
}
bool cmp(int x, int y)
{
return tin[x] < tin[y];
}
bool isAncestor(int x, int y)
{
return (tin[x]<=tin[y]&&tout[y]<=tout[x]);
}
int lca(int x, int y)
{
if (isAncestor(x,y))
return x;
if (isAncestor(y,x))
return y;
for (int i=lg-1;i>=0;--i)
if (!isAncestor(up[i][x],y))
x=up[i][x];
return up[0][x];
}
void dfsAns(int c)
{
for (auto i : e[c])
if (i[0]!=p[c][0])
{
dfsAns(i[0]);
a[c]+=a[i[0]];
}
if (a[c]>=k*2)
ans.push_back(p[c][1]);
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
int n,m,x,y;
cin>>n>>m>>k;
for (int i=1;i<n;++i)
{
cin>>x>>y;
e[x].push_back({y,i});
e[y].push_back({x,i});
}
dfs(1);
tout[0]=++t;
while (m--)
{
cin>>x;
for (int i=0;i<x;++i)
cin>>s[i];
sort(s,s+x,cmp);
s[x]=s[0];
for (int i=0;i<x;++i)
{
++a[s[i]];
++a[s[i+1]];
a[lca(s[i],s[i+1])]-=2;
}
}
dfsAns(1);
cout<<ans.size()<<"\n";
for (int i : ans)
cout<<i<<" ";
return 0;
}
