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 System.Text;
using System.Threading.Tasks;

namespace ABC_D
{
    class D069
    {
        static void Main(string[] args)
        {
            int[] b = Console.ReadLine().Split(' ').Select(z => int.Parse(z)).ToArray();
            int H = b[0], W = b[1];
            int N = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split(' ').Select(z => int.Parse(z)).ToArray();

            int[,] c = new int[H, W];
            int index = 0;
            for(int i = 0; i < N; i++)
            {
                for(int j = 0; j < a[i]; j++)
                {
                    int x = index / W;
                    int t = index % (2 * W);
                    int y = t < W ? t : 2 * W-1 - t;
                    c[x, y] = i + 1;
                    index++;
                }
            }

            for(int i = 0; i < H; i++)
            {
                string r = "";
                for(int j = 0; j < W; j++)
                {
                    if (j > 0) r += " ";
                    r += c[i, j];
                }
                Console.WriteLine(r);
            }
        }
    }

}