#include <iostream>
#include <algorithm>
#include <queue>
#include <bitset>

using namespace std;

int a[15007], suf[15007], val[15007], b[15007], ansc[15007];
pair<int, int> save[15007];
priority_queue<pair<int, int> > q;
bitset<15007> temp, bs1[15007], bs2[15007];

int main(){
	int n, max_val = 0, sum = 0, m, ansx = -1;
	cin >> n;
	for (register int i = 1; i <= n; i++){
		cin >> a[i];
		suf[a[i]]++;
		max_val = max(max_val, a[i]);
		sum += a[i];
	}
	for (register int i = max_val; i >= 1; i--){
		suf[i] += suf[i + 1];
	}
	for (register int i = 1; i <= max_val; i++){
		val[i] = val[i - 1] + suf[i];
	}
	for (register int i = max_val + 1; i <= sum; i++){
		val[i] = sum;
	}
	val[0] = -1;
	for (register int i = 1; i <= sum; i++){
		bs1[i] = bs1[i - 1];
		for (register int j = val[i - 1] + 1; j <= val[i]; j++){
			bs1[i][j] = true;
		}
	}
	cin >> m;
	for (register int i = 1; i <= m; i++){
		cin >> b[i];
	}
	bs2[0][0] = true;
	for (register int i = m; i >= 1; i--){
		for (register int j = 1; b[i] * j <= sum; j++){
			temp = bs2[j - 1];
			temp <<= b[i];
			bs2[j] |= temp;
			bs2[j] &= bs1[j];
		}
	}
	for (register int i = 1; i <= sum; i++){
		if (bs2[i][sum]){
			ansx = i;
			break;
		}
	}
	if (ansx == -1){
		cout << -1;
		return 0;
	}
	cout << ansx << endl;
	for (register int i = ansx, j = sum; i >= 1; j -= ansc[i--]){
		int pos = 1;
		while (!bs2[i - 1][j - b[pos]]) pos++;
		ansc[i] = b[pos];
	}
	reverse(ansc + 1, ansc + ansx + 1);
	for (register int i = 1; i <= n; i++){
		q.push(make_pair(a[i], i));
	}
	for (register int i = 1; i <= ansx; i++){
		cout << ansc[i] << " ";
		for (register int j = 1; j <= ansc[i]; j++){
			save[j] = q.top();
			q.pop();
			cout << save[j].second << " ";
		}
		cout << endl;
		for (register int j = 1; j <= ansc[i]; j++){
			if (--save[j].first > 0) q.push(save[j]);
		}
	}
	return 0;
}