#include <bits/stdc++.h>

constexpr int N = 1.5e4 + 5;

int32_t main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int n;
    std::cin >> n;
    std::vector<int> input(n);
    for (auto& i : input) {
        std::cin >> i;
    }
    int m;
    std::cin >> m;
    std::vector<int> sz(m);
    for (auto& i : sz) {
        std::cin >> i;
    }
    int mx = std::max_element(input.begin(), input.end()).operator*();
    int sm = std::accumulate(input.begin(), input.end(), 0);

    std::vector<std::bitset<N>> dp(sm + 1);
    dp[0][0] = 1;
    for (int i = 0; i < sm; i++) {
        for (int sh : sz) {
            dp[i + 1] |= dp[i] << sh;
        }
    }

    std::vector<int> bx_sz;
    int ind = -1;
    for (int i = mx; i <= sm; i++) {
        if (dp[i][sm]) {
            ind = i;
            break;
        }
    }

    if (ind == -1) {
        std::cout << -1 << std::endl;
        return 0;
    }

    for (int i = ind, p = sm; i > 0; i--) {
        assert(dp[i][p]);
        for (int sh : sz) {
            if (sh <= p && dp[i - 1][p - sh]) {
                p -= sh;
                bx_sz.push_back(sh);
                break;
            }
        }
    }
    assert(bx_sz.size() == ind);
    std::sort(bx_sz.rbegin(), bx_sz.rend());
    int q = ind;

    std::priority_queue<std::pair<int, int>> heap;
    for (int i = 0; i < n; i++) {
        heap.push({input[i], i});
    }

    std::vector<std::vector<int>> ans(q);
    for (int i = 0; i < q; i++) {
        std::vector<std::pair<int, int>> vec(bx_sz[i]);
        ans[i].resize(bx_sz[i]);
        for (int j = 0; j < bx_sz[i]; j++) {
            vec[j] = heap.top(), heap.pop(), vec[j].first--, ans[i][j] = vec[j].second;
        }
        for (auto p : vec) {
            heap.push(p);
        }
    }

    std::cout << ans.size() << "\n";
    for (auto vec : ans) {
        std::cout << vec.size();
        for (auto i : vec) {
            std::cout << " " << i + 1;
        }
        std::cout << std::endl;
    }

    return 0;
}