Problem:
Score : 400 points

Problem Statement

We have a grid with H rows and W columns of squares.
Snuke is painting these squares in colors 1, 2, ..., N.
Here, the following conditions should be satisfied:

For each i (1 ≤ i ≤ N), there are exactly a_i squares painted in Color i. Here, a_1 + a_2 + ... + a_N = H W.

For each i (1 ≤ i ≤ N), the squares painted in Color i are 4-connected. That is, every square painted in Color i can be reached from every square painted in Color i by repeatedly traveling to a horizontally or vertically adjacent square painted in Color i.

Find a way to paint the squares so that the conditions are satisfied.
It can be shown that a solution always exists.

Constraints

1 ≤ H, W ≤ 100

1 ≤ N ≤ H W

a_i ≥ 1

a_1 + a_2 + ... + a_N = H W

Input

Input is given from Standard Input in the following format:

H W
N
a_1 a_2 ... a_N

Output

Print one way to paint the squares that satisfies the conditions.
Output in the following format:

c_{1 1} ... c_{1 W}
:
c_{H 1} ... c_{H W}

Here, c_{i j} is the color of the square at the i-th row from the top and j-th column from the left.

Sample Input 1

2 2
3
2 1 1

Sample Output 1

1 1
2 3

Below is an example of an invalid solution:

1 2
3 1

This is because the squares painted in Color 1 are not 4-connected.

Sample Input 2

3 5
5
1 2 3 4 5

Sample Output 2

1 4 4 4 3
2 5 4 5 3
2 5 5 5 3

Sample Input 3

1 1
1
1

Sample Output 3

1

Solution in C++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
#include <iomanip>
#include <algorithm>
#include <bitset>
#include <string>
#include <cmath>
#include <complex>
#include <numeric>
#include <cassert>

#include <vector>
#include <array>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <deque>
#include <utility>

#define PI 3.14159265358979323846
#define int64 long long
#define uint64 unsigned long long
#define coutfix(i) cout << fixed << setprecision(i)		//coutの浮動小数出力の桁数設定
using namespace std;

int main()
{
	int64 hh, ww, nn, aa, pp = 0;
	cin >> hh >> ww >> nn;
	int64 memo[hh][ww];
	for(int64 ii = 1;ii <= nn;ii++)
	{
		cin >> aa;
		for(int64 jj = 0;jj < aa;jj++)
		{
			memo[pp / ww][pp % ww] = ii;
			pp++;
		}
	}
	for(int64 ii = 0;ii < hh;ii++)
	{
		if(ii % 2 == 0)
		{
			for(int64 jj = 0;jj < ww;jj++)
			{
				cout << memo[ii][jj];
				if(jj != ww - 1)
				{
					cout << ' ';
				}
			}
			cout << '\n';
		}
		else
		{
			for(int64 jj = ww - 1;jj >= 0;jj--)
			{
				cout << memo[ii][jj];
				if(jj != 0)
				{
					cout << ' ';
				}
			}
			cout << '\n';
		}
	}
	return 0;
}