#include<bits/stdc++.h>
using namespace::std;

const int N = 100000 + 5;
const int M = 1000;

int m;
int k;
int c[N];
int a[M][M];
vector<int> v;

void clear(int len){
	for(int i = 1; i <= len; i++){
		for(int j = 1; j <= len; j++){
			a[i][j] = 0;
		}
	}
}

bool check(int len){
	for(int i = 1; i + 1 <= len; i++){
		for(int j = 1; j + 1 <= len; j++){
			if(a[i][j] and a[i + 1][j + 1] and a[i][j] == a[i + 1][j + 1]) return false;
			if(a[i + 1][j] and a[i][j + 1] and a[i + 1][j] == a[i][j + 1]) return false;
		}
	}
	return true;
}

void print(int len){
	printf("%d\n", len);
	for(int i = 1; i <= len; i++){
		for(int j = 1; j <= len; j++){
			printf("%d%c", a[i][j], " \n"[j == len]);
		}
	}
}

void assign(int len){
	int pos = 0;
	for(int i = 1; i <= len and pos < v.size(); i += 2){
		for(int j = 2; j <= len and pos < v.size(); j += 2){
			a[i][j] = v[pos];
			pos += 1;
		}
	}
	for(int i = 1; i <= len and pos < v.size(); i += 2){
		for(int j = 1; j <= len and pos < v.size(); j += 2){
			a[i][j] = v[pos];
			pos += 1;
		}
	}

	for(int i = 2; i <= len and pos < v.size(); i += 2){
		for(int j = 1; j <= len and pos < v.size(); j += 2){
			a[i][j] = v[pos];
			pos += 1;
		}
	}
}

void solve(){
	int maximo = *max_element(c + 1, c +  1 + k);
	int lo = 1, hi = 200000;
	while(lo < hi){
		int mi = lo + (hi - lo) / 2;
		if(1ll * (mi - mi / 2) * mi < maximo or 1ll * mi * mi - 1ll * (mi / 2) * (mi / 2) < m){
			lo = mi + 1;
		}
		else{
			hi = mi;
		}
	}
	assign(lo);
	print(lo);
	clear(lo);
}

int main(){
	int t;
	scanf("%d", &t);
	while(t--){
		scanf("%d %d", &m, &k);
		for(int i = 1; i <= k; i++){
			scanf("%d", &c[i]);
		}
		vector<int> p(k);
		iota(p.begin(), p.end(), 1);
		sort(p.begin(), p.end(), [&] (int i, int j){
			return c[i] > c[j];
		});
		v.clear();
		for(int i : p){
			for(int j = 0; j < c[i]; j++) v.emplace_back(i);
		}
		solve();
	}
	return 0;
}

