#include <bits/stdc++.h>
#define X first
#define Y second

using namespace std;

const long long inf = 1000000000000000;
const long long MAXN = 100000+9;
const long long MAX_ANS = 500+9;

long long n, m, k, t, temp, ans, res, ok, sum, maxi, max_pos;
vector <long long> v;
long long x[MAXN], matrix[MAX_ANS][MAX_ANS];

long long f1(int n){
    if (n%2 == 0)
        return (n/2)*(n/2);
    if (n%2 == 1)
        return (n/2)*(n+1)/2;
}

long long f2(int n){
    if (n%2 == 0)
        return (n/2)*(n/2);
    if (n%2 == 1)
        return (n+1)*(n+1)/4;
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    cin >> t;
    for (int uu = 1; uu <= t; uu++){
        cin >> sum >> k;
        v.clear();
        maxi = -1;
        for (int i = 1; i <= k; i++){
            cin >> x[i];
            if (x[i] > maxi){
                maxi = x[i];
                max_pos = i;
            }
        }

        for (int i = 1; i <= 500; i++)
            if (2*f1(i) + f2(i) >= sum && f1(i) + f2(i) >= maxi){
                ans = i;
                break;
            }

        cout << ans << '\n';
        for (int i = 1; i <= x[max_pos]; i++)
            v.push_back(max_pos);
        x[max_pos] = 0;
        for (int i = 1; i <= k; i++)
            for (int j = 1; j <= x[i]; j++)
                v.push_back(i);

        temp = 0;
        for (int i = 2; i <= ans; i += 2)
            for (int j = 1; j <= ans; j += 2)
                matrix[i][j] = (temp < v.size()) ? v[temp++] : 0;
        for (int i = 1; i <= ans; i += 2)
            for (int j = 1; j <= ans; j += 2)
                matrix[i][j] = (temp < v.size()) ? v[temp++] : 0;
        for (int i = 1; i <= ans; i += 2)
            for (int j = 2; j <= ans; j+= 2)
                matrix[i][j] = (temp < v.size()) ? v[temp++] : 0;

        for (int i = 1; i <= ans; i++){
            for (int j = 1; j <= ans; j++)
                cout << matrix[i][j] << ' ';
            cout << '\n';
        }
    }
}
