#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
#define Test(tt) cout << "Case #" << tt << ": "
 
 
using namespace std;

constexpr int MAXN = 2000;

int mat[MAXN + 1][MAXN + 1];


int main() {
#ifdef HOME
    ifstream cin("A.in");
    ofstream cout("A.out");
#endif
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    int t;
    cin >> t;
    while (t--) {
        int m, k;
        cin >> m >> k;
        vector<pair<int, int>> freq(k);
        for (int i = 0; i < k; i++) {
            cin >> freq[i].first;
            freq[i].second = i + 1;
        }
        sort(freq.rbegin(), freq.rend());

        auto check = [&](int n) -> bool {
            int blue = 0, red = 0, yellow = 0;
            for (int i = 1; i <= n; i++) {
                for (int j = 1; j <= n; j++) {
                    mat[i][j] = 0;
                    if (i % 2 == 1 && j % 2 == 1) {
                        blue++;
                    } else if (i % 2 == 0 && j % 2 == 1) {
                        red++;
                    } else if (i % 2 == 1 && j % 2 == 0) {
                        yellow++;
                    }
                }
            }

            if (blue + red + yellow < m || red + blue < freq[0].first) {
                return false;
            }

            int pos = 0, cur = 0;
            for (auto it : vector<pair<int, int>>{{0, 1}, {1, 1}, {1, 0}}) {
                int x = it.first;
                int y = it.second;
                for (int i = 2 - x; i <= n && pos < k; i += 2) {
                    for (int j = 2 - y; j <= n && pos < k; j += 2) {
                        if (cur < freq[pos].first) {
                            cur++;
                            mat[i][j] = freq[pos].second;
                        } else {
                            pos++;
                            while (pos < k && freq[pos].first == 0) {
                                pos++;
                            }
                            if (pos < k) {
                                cur = 1;
                                mat[i][j] = freq[pos].second;
                            }
                        }
                    }
                }
            }

            return true;
        };

        int n = 0;
        for (int step = 1 << 9; step; step >>= 1) {
            if ((n + step) * (n + step) <= 4 * m && check(n + step) == 0) {
                n += step;
            }
        }

        cout << ++n << "\n";
        
        check(n);
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                cout << mat[i][j] << " ";
            }
            cout << "\n";
        }

        // check(2);
    }

    return 0;
}