#include <bits/stdc++.h>
using namespace std;
#define For(Ti,Ta,Tb) for(auto Ti=(Ta);Ti<=(Tb);++Ti)
#define Dec(Ti,Ta,Tb) for(auto Ti=(Ta);Ti>=(Tb);--Ti)
#define debug(...) fprintf(stderr,__VA_ARGS__)
#define range(Tx) begin(Tx),end(Tx)
using ll=long long;
const int N=15005;
int n,a[N],id[N],m,ok[N],s[N],lim[N];
bitset<N>* f[N];
vector<int> Ans[N];
int main(){
	cin.tie(nullptr)->sync_with_stdio(false);
	cin>>n;
	For(i,1,n){
		cin>>a[i];
	}
	iota(id+1,id+n+1,1);
	sort(id+1,id+n+1,[](int i,int j){
		return a[i]>a[j];
	});
	sort(a+1,a+n+1,greater<>());
	For(i,1,n){
		s[i]=s[i-1]+a[i];
	}
	cin>>m;
	For(i,1,m){
		int x;
		cin>>x;
		ok[x]=1;
	}
	For(i,1,n+1){
		f[i]=new bitset<N>[s[n]/i+1];
	}
	f[n+1][0].set(s[n]);
	Dec(i,n,1){
		For(j,0,s[n]/i){
			if(j<=s[n]/(i+1)) f[i][j]=f[i+1][j];
			if(j&&ok[i]) f[i][j]|=f[i][j-1]>>i;
			int k=s[i]-i*j;
			if(k>0) (f[i][j]>>=k)<<=k;
		}
	}
	int ans=-1;
	For(j,0,s[n]){
		if(f[1][j].test(0)){
			ans=j;
			break;
		}
	}
	if(!~ans){
		cout<<"-1\n";
		return 0;
	}
	cout<<ans<<'\n';
	int len=0;
	for(int i=1,j=ans,k=0;i<=n;++i){
		For(x,max(0,j-s[n]/(i+1)),j){
			if(f[i+1][j-x].test(k+x*i)){
				For(k,1,x){
					lim[++len]=i;
				}
				j-=x;
				k+=x*i;
				break;
			}
		}
	}
	priority_queue<pair<int,int>> q;
	For(i,1,ans){
		q.emplace(lim[i],i);
	}
	For(i,1,n){
		vector<int> idx;
		For(j,1,a[i]){
			idx.push_back(q.top().second);
			q.pop();
		}
		for(int j:idx){
			--lim[j];
			Ans[j].push_back(id[i]);
			q.emplace(lim[j],j);
		}
	}
	For(i,1,ans){
		cout<<Ans[i].size()<<' ';
		for(int j:Ans[i]){
			cout<<j<<' ';
		}
		cout<<'\n';
	}
	return 0;
}