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;

public class GridColoring
{
    public static void Main(string[] args)
    {
        int[] dimension = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
        int h = dimension[0];
        int w = dimension[1];
        int n = int.Parse(Console.ReadLine());
        int[] occuranceCountArr = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);

        int[,] result = new int[h, w];
        int rollingPointer = 0;
        for (int i = 0; i < occuranceCountArr.Length; i++)
        {
            int ai = (i + 1);
            int aiCount = occuranceCountArr[i];
            for (int c = 0; c < aiCount; c++)
            {
                int rollingRow = rollingPointer / w;
                int rollingColumn = ((rollingPointer / w) % 2 == 0) ? (rollingPointer % w) : (w - 1 - (rollingPointer % w));
                //Console.WriteLine("rollingPointer = {0}, rollingRow = {1}, rollingColumn = {2}, ai={3}", rollingPointer, rollingRow, rollingColumn, ai);
                result[rollingRow, rollingColumn] = ai;
                rollingPointer++;
            }
        }

        for (int r = 0; r < h; r++)
        {
            for (int c = 0; c < w; c++)
            {
                Console.Write(result[r, c] + " ");
            }
            Console.WriteLine();
        }
    }
}