#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//using namespace __gnu_pbds;
#define DBG(a) cerr<< "line "<<__LINE__ <<" : "<< #a <<" --> "<<(a)<<endl
#define eps 1e-8
#define eq(x,y) (fabs((x)-(y)) < eps)
using namespace std;
typedef long long ll;
typedef long long LL;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int>pii;
int mod = 1e9+7;
long double pi = acosl(-1);
const ll infl = 1e17+100;
const int inf = 1e9+100;
const int nmax = 1e5+5;
const int MAXLG = log2(nmax)+1;
//mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
//typedef tree< ll, null_type, less_equal<ll>, rb_tree_tag, tree_order_statistics_node_update> ost;


int m,k;
vector< vector<int> >arr;
vector<pii>v;
bool cmp(pii a, pii b){
    if(a.first%2 == b.first%2) return a < b;
    return a.first%2 > b.first%2;
}

bool chek(int n){

    int bhalo =  ((n+1)/2) * ((n+1)/2);
    int kharap = n*(n+1)/2 - (n+1)/2;

    if(m > bhalo + kharap) return false;
    int beshi = v[0].first;
    if( beshi-bhalo-kharap/2 > 0 ) return false;

    arr.resize(n);
    for(int i=0; i<n; i++) arr[i] = vector<int>(n, 0);
    vector<pii>gudpos;
    vector<pii>bad1;
    vector<pii>bad2;


    for(int i=0; i<n; i++) for(int j=0; j<n; j++){
        if(i%2 and j%2) continue;
        if(i%2==0 and j%2==0) gudpos.push_back({i,j});
        else {
            if(i%2)
                bad1.push_back({i,j});
            else
                bad2.push_back({i,j});
        }
    }
    vector<pii>serial;
    for(pii z : bad1) serial.push_back(z);
    for(pii z : gudpos) serial.push_back(z);
    for(pii z : bad2) serial.push_back(z);

    int cur = 0;
    for(pii z : v) if(z.first) {
        int koyta = z.first;
        int num = z.second;
        for(int j=0; j<koyta; j++){
            arr[ serial[cur].first ][ serial[cur].second ] = num;
            cur++;
        }
    }
    return true;
}


void solv(){
    cin>>m>>k;
    v.resize(k);
    for(int i=0; i<k; i++) v[i].second = i+1;
    for(pii &x : v) cin>>x.first;
    sort(v.rbegin(), v.rend());

    int lo = 1;
    while(!chek(lo)) lo++;
    cout<<lo<<"\n";
    for(int i=0; i<lo; i++){
        for(int j=0; j<lo; j++){
            cout<<arr[i][j]<<" ";
        }
        cout<<"\n";
    }
}

int main(){
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);


    int tc;
    cin>>tc;
    while(tc--){
        solv();
    }
}
/*

*/
