#include<bits/stdc++.h>

using namespace std;

#ifdef DEBUG
auto&operator<<(auto&o,pair<auto,auto>p){return o<<"("<<p.first<<", "<<p.second<<")";}
auto operator<<(auto&o,auto x)->decltype(x.end(),o){o<<"{";int i=0;for(auto e:x)o<<","+!i++<<e;return o<<"}";}
#define debug(X...)cerr<<"["#X"]: ",[](auto...$){((cerr<<$<<"; "),...)<<endl;}(X)
#else
#define debug(...){}
#endif


#define ll long long
#define pb push_back
#define st first
#define nd second
#define sz(x) (int)(x).size()
#define all(x) (x).begin(),(x).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);i++)
#define ROF(i,r,l) for(int i=(r);i>=(l);i--)
#define endl '\n'
int inf=1000000007;
ll infl=1000000000000000007;
ll mod=998244353;

int a[200000];

/*const int N=507;

int ord[N];
int a[N];
bool is[N];
int DP[N][N][N];
int zkad[N][N][N];*/

signed main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int n,m,s=0,k;
	cin>>n;
	FOR(i,1,n) 
	{
		cin>>a[i];
		s+=a[i];
	}
	cin>>m>>k;
	if(s%k!=0)
	{
		cout<<-1;
		return 0;
	}
	vector<vector<int>>ans;
	vector<int>V;
	for(int j=0;j<s/k;j++) V.pb(k);
	vector<pair<int,int>>X;
	FOR(i,1,n) X.pb({a[i],i});
	for(auto x:V) 
	{
		sort(all(X),greater<pair<int,int>>());
		vector<int>T;
		bool ok=1;
		for(int j=0;j<x;j++) 
		{
			if(X[j].st==0) ok=0;
			T.pb(X[j].nd);
			X[j].st--;
		}
		if(!ok)
		{
			cout<<-1;
			return 0;
		}
		ans.pb(T);
	}
	cout<<s/k<<endl;
	for(auto W:ans)
	{
		cout<<k<<" ";
		for(auto x:W) cout<<x<<" ";
		cout<<endl;
	}
	return 0;
}