/* Author : Mychecksdead */
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define MOD (1000000000+7)
#define MOD1 (998244353)
#define pb push_back
#define all(x) x.begin(), x.end()
#define en cout << '\n'
#define ff first
#define ss second
#define pii pair<int,int>
#define vi vector<int>
const int N = 500+100, M = 1e5+10, K = 52, MX = 30;
struct E{
bool ok;
int go;
};
int n, b[N], m, pref[N];
E DP[N][N];
array<int, 2> a[N];
pair<bool, vector<vi>> f(vector<pii> A){
vector<vi> res(A.size());
for(int i = 1; i <= n; ++i){
if(A.size() < a[i][0]){
return pair<bool, vector<vi>>{false, res};
}
for(int j = 0; j < a[i][0]; ++j){
if(A[j].ff == 0){
return pair<bool, vector<vi>>{false, res};
}
A[j].ff--;
res[A[j].ss].pb(a[i][1]);
}
sort(all(A));
reverse(all(A));
}
return pair<bool, vector<vi>>{true, res};
}
void solve(){
cin >> n;
int s = 0;
for(int i = 1; i <= n; ++i){
cin >> a[i][0];
a[i][1] = i;
s += a[i][0];
}
sort(a+1, a+1+n, greater<array<int, 2>>());
pref[0] = 0;
for(int i = 1; i <= n; ++i){
pref[i] = pref[i - 1] + a[i][0];
}
cin >> m;
vector<bool> is_size(s + 1);
for(int i = 1; i <= m; ++i){
cin >> b[i];
is_size[b[i]] = 1;
}
for(int i = 0; i <= s + 1; ++i){
for(int j = 0; j <= s + 1; ++j) DP[i][j] = {0, 0};
}
is_size[0] = 1;
int ans = MOD;
DP[n + 1][0] = {1, 0};
for(int i = 1; i <= n; ++i){ // C_{n-i+1}
for(int cur_sum = 0; cur_sum <= s; ++cur_sum){
if(s - cur_sum < pref[n-i]) break;
for(int x = 0; x <= cur_sum; ++x){
if(s - (cur_sum - x) < pref[n-i+1]) continue;
// cout << "f" << i << '\n';
bool is = is_size[n-i+1]; // x = C_{j}
int min_y;
if(!is) min_y = x;
else min_y = 0;
if(DP[n-i+2][cur_sum - x].ok && DP[n-i+2][cur_sum - x].go >= min_y && DP[n-i+2][cur_sum - x].go <= x){
DP[n-i+1][cur_sum] = {true, x};
break;
}
}
}
}
if(DP[1][s].ok){
// cout << s << ' ' << j << '\n';
vector<pii> boxes;
int cur_num = DP[1][s].go, cur_sum = s;
for(int i = 1; i <= n; ++i){
if(is_size[i]){
int old_cur_num = cur_num;
cur_num = DP[i + 1][cur_sum - cur_num].go;
if(old_cur_num > cur_num){
for(int l = cur_num; l < old_cur_num; ++l) boxes.pb({i, boxes.size()});
}
cur_sum -= old_cur_num;
}else{
cur_sum -= cur_num;
}
// cout << cur_sum << ' ' << cur_num << '\n';
}
assert(cur_sum == 0);
sort(all(boxes), greater<pii>());
auto g = f(boxes);
assert(g.ff);
cout << g.ss.size() << '\n';
for(auto v: g.ss){
cout << v.size() << ' ';
for(int u: v) cout << u << ' ';
en;
}
return;
}
cout << -1;
}
int main(){
cin.tie(0); ios::sync_with_stdio(0);
int tt = 1, aa;
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
while(tt--){
solve();
en;
}
cerr<<"time taken : "<<(float)clock()/CLOCKS_PER_SEC<<" seconds\n";
return 0;
}
