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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using static System.Console;
using System.Runtime.CompilerServices;
using static MyUtil;

class MyUtil
{
    public static int[] ReadIntArray()
    {
	return ReadLine().Split().Select(x => int.Parse(x)).ToArray();
    }
}

class Program
{
    public static void Main()
    {
	var tmp = ReadIntArray();
	int h = tmp[0], w = tmp[1];
	int n = int.Parse(ReadLine());

	int[] d = new int[h*w];
	int idx = 0;

	int[] a = ReadIntArray();
	for (int i = 0; i < n; i++)
	{
	    for (int j = 0; j < a[i]; j++)
	    {
		d[idx++] = i+1;
	    }
	}

	for (int i = 0; i < h; i++)
	{
	    string s = "";
	    int baseIdx = i * w;

	    if ((i&1) == 0)
	    {
		for (int j = 0; j < w; j++)
		{
		    if (j != 0){ s += " "; }
		    s += d[baseIdx + j].ToString();
		}
	    }
	    else
	    {
		for (int j = w-1; j >= 0; j--)
		{
		    s += d[baseIdx + j].ToString();
		    if (j != 0){ s += " "; }
		}
	    }

	    WriteLine(s);
	}
    }
}