#include <bits/stdc++.h>
using namespace std;
using pii = pair<int, int>;

void solve() {
	int m, k;
	cin >> m >> k;

	vector<pii> a;

	int ai;
	for (int i = 1; i <= k; i++) {
		cin >> ai;
		a.push_back({ai, i});
	}

	sort(a.begin(), a.end(), greater<pii>());

	int n = 1;
	for (; ; n++) {
		if (m > n * n - (n / 2) * (n / 2)) continue;
		if (a[0].first > n * ((n + 1) / 2)) continue;
		break;
	}
	
	vector<pii> pos[3];
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			int idx = ((i & 1) << 1) + (j & 1);
			if (idx != 3) 
				pos[idx].push_back({i, j});
		}
	}

	vector<vector<int>> ans(n, vector<int>(n, 0));

	for (auto [cnt, val] : a) {
		vector<pii> &curr = pos[1].empty() ? pos[2] : pos[1];

		for (; !curr.empty() && cnt > 0; cnt--) {
			auto [x, y] = curr.back();
			curr.pop_back();
			ans[x][y] = val;
		}
		for (; cnt > 0; cnt--) {
			auto [x, y] = pos[0].back();
			pos[0].pop_back();
			ans[x][y] = val;
		}
	}

	cout << n << '\n';
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			cout << ans[i][j] << ' ';
		}
		cout << '\n';
	}
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int t;
	cin >> t;

	while (t--) {
		solve();
	}

	return 0;
}
