#pragma GCC optimize("unroll-loops,O3")
#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "debug.h"
#else
#define debug(...) void(23)
#endif
template<typename T>
bool chmin(T& a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
constexpr int max_N = 3000 + 5;
int N;
int A[max_N];
int M;
int B[max_N];
int have[max_N];
std::vector<std::bitset<max_N>> dp[max_N];
int sums[max_N];
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
std::cin >> N;
for (int i = 0; i < N; ++i) {
std::cin >> A[i];
}
std::cin >> M;
for (int i = 0; i < M; ++i) {
std::cin >> B[i];
have[B[i]] = true;
}
int all = std::accumulate(A, A + N, 0);
for (int i = 0; i < max_N; ++i) {
for (int j = 0; j < N; ++j) {
sums[i] += std::min(A[j], i);
}
}
for (int i = 1; i < max_N; ++i) {
dp[i].resize(all / i + 1);
}
dp[B[M - 1]][0][0] = true;
for (int i = B[M - 1]; i >= 1; --i) {
for (int j = 0; j <= all / i; ++j) {
for (int k = 0; k <= all; ++k) {
if (!dp[i][j][k]) {
continue;
}
if (i - 1) {
dp[i - 1][j][k] = true;
}
if (have[i] && k + i <= sums[j + 1]) {
dp[i][j + 1][k + i] = true;
}
}
}
}
int cnt = 0;
while (cnt <= all && !dp[1][cnt][all]) {
cnt += 1;
}
debug(cnt);
if (cnt == all + 1) {
std::cout << "-1\n";
return 0;
}
std::vector<int> taken;
int a = 1, c = all;
for (int b = cnt; b >= 1; --b) {
while (a + 1 <= B[M - 1] && b <= all / (a + 1) && dp[a + 1][b][c]) {
a += 1;
}
debug(a, b, c);
assert(dp[a][b - 1][c - a]);
taken.emplace_back(a);
c -= a;
}
std::vector<std::vector<int>> ans;
for (auto i : taken) {
std::vector<int> p(N);
std::iota(p.begin(), p.end(), 0);
std::sort(p.begin(), p.end(), [&](auto lhs, auto rhs) {
return A[lhs] > A[rhs];
});
ans.emplace_back();
for (int j = 0; j < i; ++j) {
A[p[j]] -= 1;
ans.back().emplace_back(p[j]);
}
}
std::cout << ans.size() << '\n';
for (auto v : ans) {
std::cout << v.size();
for (auto i : v) {
std::cout << ' ' << i + 1;
}
std::cout << '\n';
}
return 0;
}
