#include<bits/stdc++.h>
using namespace std;
const int MAXN=15005;
typedef bitset<MAXN> BIT;
vector <BIT> dp[MAXN];
BIT lim[MAXN],tmp;
int up[MAXN],a[MAXN],rk[MAXN],b[MAXN];
signed main() {
	int n,m,tot=0;
	scanf("%d",&n);
	for(int i=1;i<=n;++i) scanf("%d",&a[i]),tot+=a[i],rk[i]=i;
	scanf("%d",&m);
	for(int i=1;i<=m;++i) scanf("%d",&b[i]);
	sort(rk+1,rk+n+1,[&](int x,int y){ return a[x]<a[y]; });
	sort(b+1,b+m+1,greater<int>());
	lim[0].set(0),up[0]=0;
	for(int i=1,j=0,s=0;i<=tot;++i) {
		while(j<n&&a[rk[j+1]]<i) s+=a[rk[++j]];
		up[i]=s+(n-j)*i,lim[i]=lim[i-1];
		for(int d=up[i-1]+1;d<=up[i];++d) lim[i].set(d);
	}
	dp[0].resize(1),dp[0][0].set(0);
	for(int i=1;i<=m;++i) {
		dp[i].resize(tot/b[i]+1);
		for(int j=0;j<(int)dp[i-1].size();++j) dp[i][j]=dp[i-1][j];
		for(int j=1;j<(int)dp[i].size();++j) tmp=dp[i][j-1],tmp<<=b[i],dp[i][j]|=tmp;
		for(int j=0;j<(int)dp[i].size();++j) dp[i][j]&=lim[j];
	}
	int ans=-1;
	for(int i=0;i<(int)dp[m].size();++i) if(dp[m][i][tot]) {
		ans=i; break;
	}
	if(ans==-1) return puts("-1"),0;
	printf("%d\n",ans);
	vector <int> res;
	for(int i=m,r=tot;ans;) {
		if(r>=b[i]&&dp[i][ans-1][r-b[i]]) res.push_back(b[i]),r-=b[i],--ans;
		else --i;
	}
	sort(res.begin(),res.end(),greater<int>());
	priority_queue <array<int,2>> Q;
	for(int i=1;i<=n;++i) Q.push({a[i],i});
	for(auto x:res) {
		printf("%d ",x);
		vector <int> id;
		for(int i=0;i<x;++i) id.push_back(Q.top()[1]),Q.pop();
		for(int i:id) {
			printf("%d ",i);
			if(--a[i]) Q.push({a[i],i});
		}
		puts("");
	}
	return 0;
}