#include<iostream>
#include<vector>
#include<algorithm>
#include<queue>
#include<cassert>
using namespace std;
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n;
vector<pair<int, int>> vec(n);
int sum = 0;
for(int i = 0; i < n; i++) cin >> vec[i].first, sum += vec[i].first, vec[i].second = i + 1;
cin >> m;
vector<int> poss(m);
for(int i = 0; i < m; i++) cin >> poss[i];
assert(m == 1);
sort(vec.begin(), vec.end());
if(sum % poss[0] != 0 || vec.back().first > sum / poss[0]){
cout << "-1\n";
return 0;
}
cout << sum / poss[0] << "\n";
for(int i = 0; i < sum / poss[0]; i++){
cout << poss[0] << " ";
for(int j = n - poss[0]; j < n; j++) cout << vec[j].second << " \n"[j == (n - 1)], vec[j].first--;
sort(vec.begin(), vec.end());
}
}
// g++ -std=c++17 pC.cpp -o run -fsanitize=undefined -fsanitize=address -Wall -Wextra -Wshadow
