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.Linq;

namespace ARC080
{
    class A
    {
        static void Main(string[] args)
        {

            int[] input = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int H = input[0];
            int W = input[1];

            int N = int.Parse(Console.ReadLine());

            int[] a = Console.ReadLine().Split().Select(int.Parse).ToArray();

            int count = H * W;
            int[,] HW = new int[H, W];

            int index = 1;
            int j = 0;
            for (int i = 0; i < H; i++)
            {
                if (i % 2 == 0)
                {
                    j = 0;
                    while (j < W)
                    {
                        //Console.WriteLine(a[index]);
                        HW[i, j] = index;
                        a[index - 1]--;
                        if (a[index - 1] == 0) index++;
                        j++;
                    }
                }
                else
                {
                    j = W - 1;
                    while (0 <= j)
                    {
                        HW[i, j] = index;
                        a[index - 1]--;
                        if (a[index - 1] == 0) index++;
                        j--;
                    }
                }
            }

            for (int i = 0; i < H; i++)
            {
                for (int k = 0; k < W; k++)
                {
                    Console.Write(HW[i, k]);
                    Console.Write(" ");

                }
                Console.WriteLine();
            }
        }
    }
}