#include<bits/stdc++.h>
using namespace std;
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,sse4,bmi2,popcnt")
#define int long long
#define REP(i,n) for(int i=0;i<(n);i++)
#define REP1(i,n) for(int i=1;i<=(n);i++)
#define RREP(i,n) for(int i=(n)-1;i>=0;i--)
#define RREP1(i,n) for(int i=(n);i>=1;i--)
#define f first
#define s second
#define pb push_back
#define ALL(x) (x).begin(),(x).end()
#define SZ(x) ((int)((x).size()))
#define SQ(x) ((x)*(x))
#define pii pair<int,int>
#define pipii pair<int,pii>
#define ppi pair<pii,int>
#define Graph vector<vector<int>>
#define Graphw vector<vector<pii>>
#define IOS() ios::sync_with_stdio(0),cin.tie(0)
#define md(x) (((x)%(mod)+(mod))%(mod))
#define MD(x,M) (((x)%(M)+(M))%(M))
#define ld long double
#define pdd pair<ld,ld>
#define chmax(x,y) x=max(x,y)
#define chmin(x,y) x=min(x,y)
#define addmod(x,y) x=((x+(y))%mod)
#define Vi vector<int>
#define Vpii vector<pii>
#ifdef LOCAL
#define op(x) cout<<(#x)<<"="<<(x)<<", ";
#define ope(x) cout<<(#x)<<"="<<(x)<<endl;
#define oparr(x) {cout<<(#x)<<":";for(auto allen:(x)) cout<<allen<<" ";cout<<" size="<<(x).size()<<endl;}
#define entr cout<<endl;
#else
#define op(x) ;
#define ope(x) ;
#define oparr(x) ;
#define entr ;
#endif
template<typename T1,typename T2>
ostream& operator<<(ostream& os,pair<T1,T2> p) { return os<<'{'<<p.f<<','<<p.s<<'}'; }
template<typename T1,typename T2>
istream& operator>>(istream& os,pair<T1,T2> &p) { return os>>p.f>>p.s; }
template<typename S>
ostream& operator<<(ostream& os,vector<S> p) { for(auto allen:p) os<<allen<<' ';return os<<'\n'; }
template<typename S>
istream& operator>>(istream& os,vector<S> &p) { for(auto &allen:p) os>>allen;return os; }
template<typename T1,typename T2>
pair<T1,T2> operator+(pair<T1,T2> p1,pair<T1,T2> p2) { return pair<T1,T2>(p1.f+p2.f,p1.s+p2.s); }
const int mod=998244353;
const int maxn=2e5+5;
const int maxb=20;
const int inf=1ll<<60;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rd(int l,int r) {
return uniform_int_distribution<int>(l,r)(rng);
}
struct BIT {
int n;
Vi b;
void init(int _n) {
n=_n;
b=Vi(n+1);
}
void _ud(int u,int v) {
for(;u<=n;u+=u&-u) b[u]+=v;
}
void ud(int l,int r,int v) {
_ud(l,v);
_ud(r+1,-v);
}
int qu(int u) {
int r=0;
for(;u>0;u-=u&-u) r+=b[u];
return r;
}
};
int n,m,k;
Graphw g;
Vi dfn,dfnp,dep;
Vpii dfn2;
Vi in,out,pe;
void dfs(int u,int fa) {
dfnp[u]=SZ(dfn2);
dfn2.pb({dep[u],u});
for(auto [v,id]:g[u]) {
if(v==fa) continue;
pe[v]=id;
in[id]=SZ(dfn);
dfn.pb(id);
dep[v]=dep[u]+1;
dfs(v,u);
out[id]=SZ(dfn);
dfn.pb(id);
dfn2.pb({dep[u],u});
}
}
pii st[maxb][maxn];
void st_init() {
int N=SZ(dfn2);
REP(i,N) st[0][i]=dfn2[i];
REP1(i,maxb-1) {
REP(j,N) st[i][j]=min(st[i-1][j],st[i-1][min(N-1,j+(1<<i-1))]);
}
}
int st_qu(int l,int r) {
int lg=__lg(r-l+1);
return min(st[lg][l],st[lg][r-(1<<lg)+1]).s;
}
int qu_lca(int a,int b) {
if(dfnp[a]>dfnp[b]) swap(a,b);
return st_qu(dfnp[a],dfnp[b]);
}
signed main() {
IOS();
cin>>n>>m>>k;
g=Graphw(n);
REP(i,n-1) {
int u,v;
cin>>u>>v,u--,v--;
g[u].pb({v,i});
g[v].pb({u,i});
}
dfn={-1};
pe=in=out=dfnp=dep=Vi(n);
dfs(0,-1);
st_init();
BIT bit;
bit.init(n*2+10);
auto upd_chain=[&](int a,int b,int v) {// a,b: node id
// op(a)ope(b)
bit.ud(a==0?1:in[pe[a]]+1,in[pe[b]],v);
};
auto qu_val=[&](int u) {// u:edge id
return bit.qu(in[u])-bit.qu(out[u]);
};
// oparr(pe)
// oparr(dfn)
// oparr(dfnp)
REP(i,m) {
int s;
cin>>s;
Vi a(s);
REP(j,s) cin>>a[j],a[j]--;
sort(ALL(a),[&](int x,int y) {return dfnp[x]<dfnp[y]; });
// oparr(a)
Vi b;b.pb(a[0]);
REP1(j,s-1) {
// op(a[j-1])ope(a[j]);
b.pb(qu_lca(a[j-1],a[j]));
// op(i)ope(j)
b.pb(a[j]);
}
// op(i)ope("ok")
sort(ALL(b),[&](int x,int y) {return dfnp[x]<dfnp[y]; });
b.erase(unique(ALL(b)),b.end());
// oparr(b)
REP1(j,SZ(b)-1) {
upd_chain(qu_lca(b[j],b[j-1]),b[j],1);
}
}
Vi an;
// REP(i,n-1) cout<<qu_val(i)<<' ';entr
REP(i,n-1) if(qu_val(i)>=k) an.pb(i);
cout<<SZ(an)<<'\n';
for(int x:an) cout<<x+1<<' ';
cout<<'\n';
return 0;
}
